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1.
In response female pheromone the male gypsy moth flies a zigzagging path upwind to locate the source of odor. He determines wind direction visually. To learn more about the mechanism underlying this behavior, we studied descending interneurons with dye-filled micro-electrodes. We studied the interneuronal responses to combinations of pheromone and visual stimuli.
1.  We recorded 5 neurons whose directionally selective visual responses to wide field pattern movement were amplified by pheromone (Figs. 2–6).
2.  The activity of the above neurons was more closely correlated with the position of the moving pattern than with its velocity (Fig. 4).
3.  One neuron showed no clearly directional visual response and no response to pheromone. Yet in the presence of pheromone it showed directionally selective visual responses (Fig. 6).
4.  We recorded 4 neurons whose directionally selective visual responses were not modulated by pheromone (Fig. 7), ruling out the possibility that the effect of the pheromone was simply to raise the activity of all visual neurons.
5.  Our results suggest that female pheromone amplifies some neural pathways mediating male optomotor responses, especially the directionally selective responses to the transverse movement of the image, both below and above the animal.
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2.
1.  Stimulation to left and right vagi caused an almost equal amount of inhibitory, and occasionally excitatory, effects on pacemaker activity. Both inhibitory and excitatory effects were abolished by atropine. Vagal stimulation hyperpolarized the resting membrane potential of pacemaker fibers in the sino-atrial valve, but did not change their action potential profile.
2.  The atrial action potential showed a prominent decrease in the action potential amplitude and duration in response to vagal stimulation. The atrial region surrounding the sino-atrial valve was more sensitive to right vagal stimulation.
3.  The fibers in the atrio-ventricular ring muscle were less sensitive to vagal stimulation than the atrial fibers. Some fibers showed a decrease in the action potential amplitude and duration by vagal stimulation, and other fibers showed a decrease in the amplitude, but a prolongation of the duration as the result of a slowing of the rate of upstroke. The atrial-ventricular conduction delay or block by vagal stimulation may depend on these properties of the action potential of the atrio-ventricular ring muscle.
4.  The sino-atrial conduction block is explained by the fact that the atrial fibers are more sensitive to vagal stimulation than pacemaker fibers.
5.  The possible pathways for the sino-ventricular conduction during vagal stimulation are discussed.
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3.
Locusts (Locusta migratoria) were flown in a flight simulator which converts yaw torque into angular motion of the visual environment (Fig. 1). The modalities and the time-course of steering behavior under these closed-loop conditions have been investigated.
1.  Locusts flying under visual closed-loop conditions stabilize their visual environment by performing correctional steering manoeuvres. Besides torque production, due to differential wing movements and ruddering, correctional steering also involves head movements (Fig. 6).
2.  During open-loop steering, ruddering and yaw torque begin some 60 ms after the onset of the visually simulated deviation from course. Head movements occur some 90 ms after stimulus onset, i.e. some 30 ms later than yaw torque (Figs. 3, 5) and therefore do not initiate thoracic steering outputs.
3.  Open- and closed-loop correctional steering do not differ in their behavioral components or temporal organization (Figs. 2, 6, Table 1).
4.  In the absence of major disturbances, correctional steering under closed-loop conditions is performed with minimal ruddering (only a few degrees in amplitude), that probably produces little or no aerodynamic drag (Fig. 6).
5.  Locusts prevented from moving their heads still stabilize their visual environment in the closed-loop situation. However, the precision of steering is affected by this constraint (Figs. 8, 9, 10, 12). Head immobilization also alters the temporal coordination of correctional steering (Figs. 7, 11).
6.  These results show that head movements, in addition to their generally accepted role in vision improvement, also contribute to the precision and temporal coordination of correctional flight manoeuvres. The mechanism is partly via proprioceptive feedback.
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4.
1.  The European hawk moth Macroglossum stellatarum, while collecting nectar in hovering flight in front of flowers, follows moving stripe patterns in the lateral visual field. This response counteracts a second one, that is the animals' effort to stabilize their distance from dummy flowers. We investigated the response to motion stimuli in the lateral visual field using sinusoidally oscillating stripe patterns (Fig. 1), as well as its interaction with the distance stabilizing response.
2.  In both responses moths attempt to compensate for image speed. The balance between the two depends on the number of elementary motion detectors stimulated by the dummy flower and the stripe pattern, respectively. Increasing the diameter of the dummy flower (Figs. 2 to 4) or the spatial frequency of the stripe pattern (Fig. 7) shifts the balance in favour of distance stabilization. The reverse is true when the length of the stripes in the pattern (Fig. 5) or their number is increased (Fig. 6). It does not matter whether the stripe pattern is presented in the lateral (Fig. 4A) or in the dorsal and ventral visual field (Fig. 4B).
3.  The gain-frequency relations of the response to the lateral stripe pattern obtained with dummies in two different positions within the drum have their maxima around 3 Hz and decline rapidly towards lower and higher frequencies like the response of a bandpass filter. The distance stabilizing response also has bandpass properties, but with a broad plateau between 0.15 and 5 Hz (Fig. 8). The most likely explanation for this difference is that there is a regional or direction-dependent variation of motion detector properties.
4.  The responses to ramp-like stimuli are phasic in accordance with the amplitude frequency characteristics, but the responses to progressive (front to back) and regressive motion of the pattern differ (Figs 9, 10).
5.  The response appears to depend on the azimuthal position of the stripe pattern within the visual field (Fig. 11). It is strongest when the pattern covers equally large parts of the frontal and caudal visual fields. The optomotor sensitivity to translational pattern motion is higher in the frontal than in the caudal visual field (Fig. 12, Table 1).
6.  When the stripe pattern on one side is removed, the response amplitude is halved. There is no detectable turning response around the vertical axis to the oscillation of the stripe pattern (Fig. 13, Table 2).
7.  The possible role of the response to pattern movements parallel to the longitudinal body axis under natural conditions is discussed.
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5.
1.  We recorded compensatory eye stalk movements in response to pitch and roll stimulation of the visual, statocyst, and leg-proprioceptive systems in different species of crabs (Carcinus maenas, Heloecius cordiformis, Pachygrapsus marmoratus) (Fig. 2).
2.  The relative contribution of visual, statocyst and leg-proprioceptive inputs to eye stabilization in space varies greatly among different species (Fig. 3).
3.  We suggest that for stabilizing the eyes in space, the contribution of various sensory inputs in different species of crabs correspond to the availability of cues in their habitat. Semiterrestrial crabs living in a habitat with well defined and predictable visual geometry stabilize their eye stalks mainly by visual cues. Crabs living on solid substrate make strong use of leg proprioceptive input. Swimming crabs, and other predominantly aquatic crabs, rely mainly on their statocysts.
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6.
1.  Most Purkinje neurons show ongoing spike activity. In approximately 75%, this activity disappeared after peduncle lesion and in some of these the activity stopped when water flow over the gills was interrupted. Approximately one-fourth of Purkinje cells (PC's) showed continuing ongoing activity after afferent input was abolished.
2.  Stimulation of spinal cord elicited both simple spikes, mainly in ipsilateral PC's, and some complex responses (via climbing fibers) usually contralateral and of longer latency than the simple spikes.
3.  Tactile stimulation of skin and flexion of tail or fins, also lateral line stimulation by a water stream, evoked bursts of spikes in PC-s. Input was by mossy fibers and mechanoreceptive fields were large.
4.  Stimulation of vestibular nerve produced both simple and complex responses in PC's. Auditory stimuli were most effective at 800–1200 Hz in eliciting responses via mossy fibers. Responses to sound were phasic changes in ongoing frequency, bursts followed by inhibition or on-off excitation.
5.  Responses to visual stimuli were recorded in granule cells and Purkinje cells, also in mossy axons. Many PC's showed excitatory-inhibitory sequences; a few climbing fiber responses were recorded. The mossy fiber visual input is from optic tectum relay.
6.  Some PC's were activated by two or three sensory modalities.
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7.
1.  In this commentary we discuss results obtained by a micromethod for the study of Cl– permeability across single nerve membranes from rabbit Deiters' neurons.
2.  These results showed the presence of GABAA receptors on the nerve cell membrane cytoplasmic side.
3.  We could show that these receptor complexes have a higher affinity for GABA than their extracellularly facing counterparts. Moreover, they present a phenomenon of desensitization. Another distinct property is that upon activation by GABA, they expose positive charges at their cytoplasmic mouths.
4.  We propose that these receptor complexes could functionin situ as a device for extruding Cl– anions from the nerve cell interior. This phenomenon would create an electrochemical gradient for Cl– penetration into the cell upon the action of extracellular GABA, after its presynaptic release.
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8.
1.  While collecting nectar in hovering flight the European hawk moth Macroglossum stellatarum efficiently regulates its distance relative to flowers that are shaken by wind. This can be demonstrated in laboratory experiments by moving dummy flowers (blue cardboard disks) towards and away from the feeding animal (Fig. 1).
2.  Distance regulation is predominantly mediated by visual cues. Mechanoreceptors on the proboscis appear to contribute little to the response.
3.  Movements of dummy flowers can be simulated by expanding and contracting a pattern projected onto a screen. With this technique we investigated the dynamical properties of the servo mechanism underlying distance regulation. The system behaves as a bandpass filter with corner frequencies of 0.15 and 5 Hz (Figs.2,3).
4.  When a high-speed ramp-like movement of the flower is simulated, there is an asymmetry in the response. During simulated approach the reaction is phasic-tonic with a pronounced overshoot at the beginning, during simulated retraction it remains tonic (Fig.5B,C).
5.  During distance regulation the animals compensate for the speed of the edge of the projected pattern. Distance regulation improves substantially when the number of stimulated elementary movement detectors is increased through increasing the number of contour lines by projecting concentric rings instead of a homogeneous disk (Figs.7, 8).
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9.
1.  By penetrating axons in the ventral nerve cord of the dragonfly, Aeshna umbrosa, we measured the intracellular responses of target-selective visual interneurons to movement of black square targets ranging from 1° to 32° visual angle at several levels of mean background luminance.
2.  Neuronal responses, measured both in number of spikes and in the magnitude of integrated postsynaptic potentials, showed a preference for larger target size at lower mean luminance (Table 1, Figs. 1–3). The latency of postsynaptic potential (psp) and spike responses from onset of target movement increased with a decrease in mean luminance (Fig. 1).
3.  A measure of mean target size preference (Eqn. 1) for one identified interneuron (MDT4) in both laboratory and outdoor lighting shows a continuous decrease of preferred size with increases of mean luminance over more than 4 orders of magnitude.
4.  The time to reach the new steady state of cell response after the decrease of mean luminance was ordinarily less than 30 s, but sometimes longer (Fig. 4).
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10.
1.  The activity of tympanal high- and low-frequency receptors in the migratory locustLocusta migratoria was recorded with glass capillary microelectrodes, and Lucifer Yellow was then injected through the microelectrode to reveal the cells' metathoracic projections.
2.  A photodetector device was used to monitor the abdominal respiratory movements, which caused clearly visible deflections of the tympanal membrane.
3.  The auditory receptors respond not only to sound stimuli but also to the respiratory movements; these phasic (Figs. 1–3) or tonic (Fig. 4) responses are especially pronounced during the inspiration and expiration movements, and less so during the constriction phases.
4.  The magnitude of the response to sound depends on the phase of the stimulus with respect to the respiratory movements. At certain phases sound elicits no response at all (Fig. 5).
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11.
1.  The terminal ganglion ofLocusta migratoria contains a number of non-giant, wind-sensitive, ascending and local interneurones. Six ascending (Figs. 1, 2) and 6 local (Figs. 6, 7) interneurones have been identified morphologically on the basis of intracellular stains with Lucifer Yellow.
2.  The physiological responses of the various cell types were recorded as the cerci were exposed to sound, wind, or electrical stimulation (Figs. 3, 8). Some cells summate the input from both cerci (Fig. 3), while others are excited by input from one side and inhibited by input from the other (Fig. 8). Conduction velocities for several non-giant ascending interneurones range from 1.5 m/s (cell 1) –2.1 m/s (cell 25).
3.  The morphologies and physiological responses of giant (GIN 1) and non-giant ascending interneurones (cells la, b) with somata in cluster 1 of neuromere 9 were compared using simultaneous intracellular recordings (Figs. 2A, 4). These neurones have very similar dendritic arborizations (Fig. 4A, B), and respond almost identically to cercal stimulation (Fig. 4Ci), but there do not appear to be any connections with GIN 1 (Fig. 4Cii, iii).
4.  The morphology (Fig. 5A, C), and response to cercal stimulation by wind (Fig. 5B) of a nongiant interneurone (cell 7) with its soma in cluster 1 of segment 8 (Fig. 5), are very similar to those of cluster 1 cells such as GIN 1 in segment 9.
5.  Of the 6 local interneurones (Figs. 6, 7) all except one (cell 9) have bilateral arborizations which may extend over several neuromeres within the ganglion (cells 10, 22). Several of the interneurones (cells 5, 9, 24) do not produce action potentials in response to cercal stimulation (Figs. 8, 10) or injection of depolarizing current (Fig. 11).
6.  Simultaneous recordings from pairs of interneurones demonstrate that giants and locals (GIN 2/cell 5; GIN 1/cell 9), as well as different local interneurones (cell 24/cell 5), receive input from the same wind-sensitive filiform afferent (Fig. 9).
7.  Local interneurones 5 and 22 are in different neuromeres of the terminal ganglion but have a similar gross morphology (Figs. 6, 7, 10). Cell 5, however, has arborizations projecting into both posterior cercal glomeruli (Fig. 7 A, inset), whereas only the ipsilateral branches of cell 22 extend posteriorly to the cercal glomerulus (Fig. 10C). Physiologically, cell 5 is depolarized by wind directed at both cerci (Fig. 10 A), cell 22 mainly by wind directed at the ipsilateral cercus (Fig. 10C). Cell 5 does not produce action potentials in response to wind whereas cell 22 does.
8.  Cell 5 occurs as a bilateral pair in the terminal ganglion (Figs. 7B, inset; 11). Simultaneous recordings of the bilateral homologues show that they share the input of at least one wind-sensitive filiform afferent (Fig. 11D), and that there are no connections between them (Fig. 11E). Simultaneous penetrations of local interneurone 5 and giant interneurones demonstrate a short-latency excitatory connection from GIN 3 to cell 5 (Fig. 12 A), and a long-latency excitatory connection from GIN 2 to cell 5.
9.  The roles of giant and non-giant interneurones in transmitting information to thoracic motor centres are discussed.
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12.
1.  Interactions of cockroaches with 4 different predator species were recorded by videography. Some predators, especially spiders, struck from relatively short distances and usually contacted a cockroach prior to initiation of escape (Table 1, Fig. 3). This touch frequently occurred on an antenna. Cockroaches turned away from the side on which an antenna was touched.
2.  We then measured the success of escape from predators for cockroaches with either cerci or antennae ablated. Only antennal removal caused a significant decrease in the success of escape from spiders (Fig. 5).
3.  With controlled stimuli, cockroaches responded reliably to abrupt touch of antennae, legs or body (Fig. 6). Responses resembled wind-elicited escape: they consisted of a short latency turn (away from the stimulus) followed by running (Figs. 7, 8). However, lesions show that touchevoked escape does not depend on the giant interneuron system (Table 2).
4.  Following section of one cervical connective, cockroaches continued to respond to touching either antenna, but often turned inappropriately toward, rather than away from, stimuli applied to the antenna contralateral to the severed connective (Table 3, Fig. 10).
5.  For certain types of predators touch may be a primary cue by which cockroaches detect predatory attack. Descending somatosensory pathways for escape are distinct from the GI system.
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13.
1.  The diffusive hydrogen conductance of chicken eggshell compound membrane was measured in situ on day 16 of incubation, in a direction parallel to the shell and the chorioallantois (lateral conductance). A value of 3.9 mmol d–1 kPa–1 was obtained through a ring 13.29 cm in circumference, 0.0076 cm thick and 0.3 cm long.
2.  Lateral hydrogen conductance for 1 mm2 of shell membrane 76 m thick is 30 times the conductance of one pore serving the same area.
3.  Lateral conductance for H2 is not significantly influenced by chorioallantoic perfusion.
4.  Oxygen consumption change due to partial covering of the hen eggshell indicates that there is a significant resistance to lateral diffusion of oxygen under the shell toward the covered area.
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14.
In the grasshopperChorthippus biguttulus the stridulatory movements of males with surgically manipulated ventral nerve cords were investigated.
1.  The stridulation pattern of animals with a hemisected mesothoracic ganglion was indistinguishable from that of intact animals.
2.  After hemisection of the metathoracic ganglion several animals were still able to stridulate in the species-specific pattern (Figs. 3, 5). Different structural elements of the song, however, were affected to different degrees by this operation. Although the stereotyped up-and-down movements were normal, the rhythm of pauses, which in intact animals are inserted after every third to fourth up- and-down cycle, was disturbed. As a result, the variation of syllable lengths was much higher (Fig. 4).
3.  A prominent feature after hemisection of the metathoracic ganglion was an almost complete loss of coordination between left and right hind legs (Figs. 5–7). Only in the coarse structure of the song (e.g. the beginning and termination of song sequences) was a correlation of the leg movements still discernible. This was especially obvious in songs of the rivalry type and in precopulatory kicking movements (Fig. 8).
4.  If in addition to hemisection of the metathoracic ganglion one of the neck connectives was transected the animals stridulated only with the hind leg ipsilateral to the intact connective (Fig. 11).
5.  Even after hemisection of both the meso- and metathoracic ganglia, animals were able to produce the species-specific stridulation pattern (Fig. 9).
6.  In animals with hemisected metathoracic ganglia and both connectives between pro- and mesothoracic ganglia transected, components of the species-specific pattern could be induced by current injection into the mesothoracic ganglion (Fig. 10).
7.  These results suggest that the stridulation rhythm-producing neuronal network is composed of hemisegmental subunits. A hemiganglionic structure of rhythm generators might reflect the ancestral organization of locomotion-controlling networks.
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15.
1.  Certain species of tiger moths emit clicks when stimulated by bat-like sounds. These clicks are generated by modified thoracic episterna (tymbals) (Fig. 1) and constitute a rhythmic behaviour activated by simple sensory input.
2.  Tymbal periods are indirectly related to stimulus intensity and periods (Fig. 3). Moths initiate sounds with the tymbal opposite to the stimulated ear and once a sequence commences it continues in an undisrupted fashion.
3.  The tymbal is innervated by a pleural branch (IIIN2a) of the metathoracic leg nerve, a similar anatomy to that in the unmodified episterna of silent moths (Fig. 5). Backfills of the IIIN2a in Cycnia tenera reveal sensory fibres and a cluster of 5–9 motor neurons with densely overlying dendritic fields (Fig. 6).
4.  Extracellular recordings of the IIIN2a reveal a large impulse preceding each tymbal sound (Fig. 7). I suggest that this impulse results from the synchronous firing of 2–3 motor neurons and is the motor output of the tymbal central pattern generator (CPG). The spikes alternate (Figs. 9, 10) and are bilaterally co-related (Fig. 11) but with an phase asymmetry of 2–3 ms (Fig. 12).
5.  Normal motor output continues in the absence of tymbal sounds (Fig. 13) and when all nerve-tymbal connections are severed (Fig. 14, Table 1) therefore this CPG operates independent of sensory feedback. A model is proposed for the tymbal circuitry based upon the present data and the auditory organization of related noctuid moths (Fig. 15). I propose that the tymbal response in modern arctiids evolved from either flight or walking CPGs and that preadaptive circuitry ancestral to tymbal movements still exists in modern silent Lepidoptera.
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16.
1.  Bees were trained to enter the central hole in a disc containing 89 holes and collect sugar-water from a box placed behind it (Fig. 1). Visual marks were offered on the inner surface of a cylinder placed in front of the disc (Fig. 2), thus projecting onto peripheral (nonfrontal) regions of the bees' eye. The trained bees were tested by recording their choices among the holes.
2.  Bees use the memorized position of peripheral marks to localize the frontally positioned goal (Figs. 6–9). The effectiveness of a mark depends on its retinal position, the most effective marks being lateral ones (Figs. 8, 9).
3.  Altering the dimensions of the mark does not influence the distribution of the bees' choice (Figs. 11–13). Thus, image motion rather than image size is used for distance estimation in the present task.
4.  Cinematographic recordings (Fig. 14) revealed that the searching bees' whereabouts are correlated with the choice distribution (Fig. 6a). The hypothesis that the bees stabilize the mark in the trained retinal position by correcting for retinal image slip is proposed.
5.  Experiments using coloured patterns revealed that the bees' performance is mediated by the green-sensitive channel (Figs. 17–22), as predicted by the above hypothesis.
Dedicated to Prof. Dr. Rüdiger Wehner on the occasion of his 50th birthday, in great appreciation for both his scientific work and his personality.  相似文献   

17.
1.  The behaviour of isolated individual forager honeybees during the night has been investigated with a variety of experimental methods. Prolonged rest in these diurnal insects is accompanied by: reduced muscle tone (Figs. 1, 6, 10–12), decreased motility (Figs. 2, 3, Table 1), lowered body temperature (Figs. 7, 8) and raised reaction threshold (Fig. 9). These phenomena strongly resemble four characteristic features of sleep in humans, mammals and birds. It is thus very likely that the profound rest which forager bees experience at night is sleep. This assumption is further supported by the results of previous investigations of visual interneurones in the bee.
2.  The antennae of sleeping bees manifest characteristic postural constellations (Fig. 6). High reaction thresholds are associated with particular antennal positions.
3.  The total sleep time (duration of antennal immobility plus duration of small antennal movements) in 24 h for two bees was 7.6 h and 4.9 h (Table 1).
4.  Bees which rest in a hive at night also display phenomena which have been encountered during the laboratory investigations.
5.  Sleep in mammals is an active, controlled process; the same seems to be true of sleep in honeybees (Figs. 3, 4). Unlike mammals, bees experience their deepest sleep towards the end of the sleep phase (Figs. 3, 9, 10, 12).
Dedicated to Prof. Dr. D. Burkhardt on the occasion of his 60th birthday  相似文献   

18.
1.  Spikes in Aplysia MA1 neurons produced excitatory (EJPs), inhibitory (IJPs), and diphasic inhibitory-excitatory junction potentials in different fibers of the buccal muscles.
2.  The IJPs following the MA1 spikes were recorded in the muscle fibers innervated by the jaw-closing motoneurons. The depolarization of muscle fibers produced by the motoneurons was largely suppressed by simultaneous MA1 firing, suggesting that the MA1 neurons make a direct connection to a part of the muscle fibers innervated by these motoneurons and inhibit them.
3.  The excitatory and inhibitory components of the junction potentials produced by MA1 were reversibly blocked by hexamethonium and d-tubocurarine, respectively. In contrast, the EJPs produced by the jaw-closing motoneurons were blocked by an amino acid antagonist, suggesting that the MA1 neurons and the jaw-closing motoneurons use different transmitters in the nerve-muscle junctions.
4.  The jaw movement produced by the jaw-closing motoneurons was suppressed by simultaneous MA1 firing, and the suppression was released by d-tubocurarine, suggesting that the IJPs produced by MA1 may contribute to the suppression of jaw movement. The firing of MA1 produced the vertical movement of the buccal muscles, which was blocked by hexamethonium, suggesting that the EJPs produced by MA1 may contribute to the vertical movement.
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19.
1.  Intracellular recordings of suboesophageal neurons were performed in the cricketGryllus bimaculatus during applied changes of head temperature in the range 8 to 32.5 °C. The temperature was controlled by perfusing the head with Ringer solution of appropriate temperature. Subsequent staining with Lucifer Yellow revealed descending, ascending or T-shaped cells with ventrally located somata (Fig. 1).
2.  In 6 out of 7 neurons recorded (Fig. 1, neurons A, B, C, D, E, G) the firing rate was correlated with abdominal ventilatory pumping (Fig. 2a, b). These neurons also received input from cereal sensory hairs (Fig. 2c). Furthermore, one of them (Fig. 1, neuron A) showed responses to auditory (Fig. 2d) and another (Fig. 1, neuron E) to visual input (Fig. 2e).
3.  Activity of every tested neuron was correlated with the temperature of the perfusing Ringer solution: the amplitude and duration of spikes and excitatory postsynaptic potentials increased with cooling (Fig. 3). Two types of temperature-dependent changes in firing rate were identified. In type I the spiking rate was higher at higher temperature (Figs. 4a, b; 5). In type II spiking rate was related to the direction of temperature change (Fig. 4c, d).
4.  The possible involvement of one of the recorded cells (Fig. 1, neuron F) in thermoreception processes is discussed. Activity of this neuron was not related to the rhythm of abdominal ventilatory pumping, nor did the cell receive cereal, visual or auditory input. Its activity was related mainly to the direction of temperature changes i.e. with an increase in firing rate during cooling, independent of the temperature at which the cooling started and with a transient decrease in firing rate during warming from starting point of 10 °C.
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20.
1.  The activities of glycolytic enzymes and of related enzymes of anaerobic carbohydrate metabolism were determined inTubifex. The complete line of glycolytic enzymes was detected (Table 1). Only very little lactate dehydrogenase activity could be detected, while high activities of enzymes essential for the production of alanine and succinate are present.
2.  Under anaerobic conditions, lactate, alanine, succinate and volatile fatty acids are formed from14C-labeled glucose (Tables 2 and 3).
3.  Glycogen degradation was measured under anaerobic conditions (Fig. 1).
4.  During anaerobiosis a significant increase of alanine, succinate, propionate and acetate was found. However, the concentration of lactate increased only slightly. After an initial increase within the first 24 h of anaerobiosis, the concentration of alanine remained constant. Succinate, on the other hand, accumulated continuously during 48 h of anaerobiosis, reaching concentrations of 150 mol/g dry weight (Table 4, Fig. 2).
5.  The major end products of fermentation were identified as propionate and acetate. Both are excreted in substantial amounts (Table 5).
6.  The amount of anaerobic end products equals the amount of glycogen metabolized (Table 6).
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