STUDIES OF THE INNER AND OUTER PROTOPLASMIC SURFACES OF LARGE PLANT CELLS : II. MECHANICAL PROPERTIES OF THE VACUOLAR SURFACE

The vacuolar surface of Nitella is covered with a non-aqueous film too thin to be visible as a separate membrane. The motion of the protoplasm may subject this film to a good deal of mechanical disturbance. Apparently this does not rupture the film for no dye escapes into the protoplasm as the result of such disturbance when the vacuolar sap is deeply stained with neutral red or brilliant cresyl blue. When the deeply stained central vacuole breaks up into several smaller vacuoles, leaving the outer protoplasmic surface in its normal position, there is no evidence of the escape of dye into the protoplasm through the film surrounding the vacuole.     

THE FINE STRUCTURE OF THE ELECTRIC ORGAN OF TORPEDO MARMORATA

The fine structure of the electric organ of the fish Torpedo marmorata has been examined after osmium tetroxide or potassium permanganate fixation, acetone dehydration, and Araldite embedment. This organ consists of stacks of electroplaques which possess a dorsal noninnervated and a ventral richly innervated surface. Both surfaces are covered with a thin basement membrane. A tubular membranous network whose lumen is continuous with the extracellular space occupies the dorsal third of the electroplaque. Nerve endings, separated from the ventral surface of the electroplaque by a thin basement membrane, contain synaptic vesicles (diameter 300 to 1200 A), mitochondria, and electron-opaque granules (diameter 300 A). Projections from the nerve endings occupy the lumina of the finger-like invaginations of the ventral surface. The cytoplasm of the electroplaques contains the usual organelles. A "cellular cuff" surrounds most of the nerve fibers in the intercellular space, and is separated from the nerve fibre and its Schwann cell by a space containing connective tissue fibrils. The connective tissue fibrils and fibroblasts in the intercellular space are primarily associated with the dorsal surface of the electroplaque.     

CONCERNING THE INFLUENCE OF POLARIZED LIGHT ON THE GROWTH OF SEEDLINGS

While these experiments are not exhaustive, a sufficient number have been made to warrant the statement that the effect of polarized light of the visible spectrum on the growth of various seedlings and See PDF for Structure more particularly on the growth of Lupinus albus is somewhat different from that of non-polarized light. This is especially convincing in view of the results obtained with double sets of plants which were alternately exposed to polarized and non-polarized lights of the same intensities and at the same temperature. In every experiment thus performed the set which was placed in a polarizing chamber grew better. It is, furthermore, interesting to note that the phenomenon above observed did not take place when the seed portion of the plants was protected from light by wrapping with tinfoil. This agrees well with previous findings concerning the action of diastase on starch in polarized light. The above researches will be continued on a more elaborate scale but the results so far obtained are deemed worthy of publication in the form of a preliminary communication at the present time.     

RAPTOR MIGRATION ACROSS THE STRAITS OF GIBRALTAR

The visible migration of birds of prey at Gibraltar is analysed from records kept throughout the spring passages of 1967–70 and the autumn passages of 1967–69. In early spring most visible passage is noted in the afternoons, whereas radar observations by Houghton (1970) indicate passage in the mornings. Later in the year an additional burst of visible passage sometimes occurs in the early morning, but it is concluded that most morning movements take place above visible range. Visible migration is recorded on most days of westerly wind during the migration seasons at Gibraltar. Passage is rarely seen when the winds are easterly. It is argued that under the latter conditions a strong upcurrent of air (standing wave) is formed over Gibraltar, and that this carries nearly all migrants above visible range.
Observations of visible passage elsewhere in the Straits suggest that, in spring, raptors of all species cross on a broad front from Tangier to Ceuta, except Honey Buzzards, which probably cross chiefly near Ceuta. In autumn, all species from northern Europe cross chiefly between Tarifa and to the east of Gibraltar, while birds from western Iberia probably cross mainly near Tarifa.
The periods of passage of the common migrant species are summarised.
On the basis of visual observations and published radar results, it is argued that raptors can compensate for lateral drift by the wind and so fly on chosen courses; but that in very strong cross-winds, e.g. the easterly Levanters, they may have to let themselves be drifted off-course.     

METASTATIC CARCINOMA OF THE THYROID GLAND AS THE INITIAL MANIFESTATION OF THE DISEASE

During the past 38 years, 260 patients with thyroid carcinoma have been operated upon at the University of California Hospital. In 26 of these patients the first symptom was a mass distant from the thyroid gland, and the gland was considered normal on clinical examination.In all but three of the 26 cases a small carcinoma of the thyroid gland was observed at operation or in pathological examination.Radical neck dissection with either total lobectomy or total thyroidectomy would seem to be the operation of choice in the treatment of these patients.The ultimate prognosis, even in the presence of metastases, is relatively good.Primary carcinoma of the thyroid gland should be considered in the presence of tumors of the side of the neck even in the absence of palpable nodules in the gland itself.     

THE ERECT LATERAL LUMBAR ROENTGENOGRAM IN THE EVALUATION OF “LOW BACK” PAIN

A study was made of the potential value of the erect lateral flexion lumbar roentgenogram in a series of 50 adults, some with symptoms of low back pain and some without such symptoms. The film was made in addition to the standard antero-posterior, lateral and sometimes oblique views taken in the recumbent position.In 11 of 37 patients with low back pain, some narrowing of lumbar discs was visible in both horizontal and erect lateral films, the degree being not significantly different between the two positions. In one patient, localized anterior narrowing of a lumbar disc, which was not visible in the recumbent lateral film, was observed. This finding was confirmed at a subsequent examination.In one of 13 patients without lumbar area symptoms, slight anterior narrowing of a lumbar disc could be seen in the erect lateral film but not in the horizontal. The reason for this is not known; it may be physiologic in this particular patient.The value of the routine erect lateral flexion lumbar roentgenogram was not confirmed by this preliminary study.     

CIGARETTE SMOKING AND CANCER OF THE LUNG—Is There Really Any Etiologic Relationship?

Many past, widely accepted medical beliefs have subsequently proved to be false. Although much has been written about possible causal relations of cigarette smoking to lung cancer, there is a good deal of evidence which does not fit this hypothesis.This report summarizes some of the reasons for believing that cigarette smoking is not an important etiologic agent in lung cancer. Recent studies have reemphasized the importance of genetic factors, and a large number of significant psychologic variables between smokers and nonsmokers. The mounting evidence incriminating air pollution must also be borne in mind.     

壳斗科木材识别和分类

从106种壳斗科木材构造特征.作为本科木材识别和分类依据,概括于下: 散孔材,管孔细,单个密布,在生长轮末端一狭带无管孔,宽射线为多列射线,较狭而数较多为水青冈属。辐射孔材,管孔成串径列,宽射线聚合型,在横面反光弱为主,分布不均,促使材身槽棱不整齐,槽底平而宽长的为稠属。辐射孔材,管孔成串径、斜列为主,宽射线聚合型(常见)和栎型,在横面反光强,分布均匀,促使材身槽棱整齐,槽底尖而分隔为青冈属。半环孔材或环孔材,早材管孔沿生长轮不连续排列,在肉眼下可见至明显,晚材管孔成串径列,弯曲或火焰状,宽射线聚合型,常数少且几条聚近分布,大部分树种无宽射线的为锥属。环孔材,早材管孔沿生长轮连续排列,肉眼下明显,侵填体丰富,晚材管孔成串径列,弯曲或火焰状,宽射线栎型为栎属。环孔材,早材管孔沿生长轮连续排列,肉眼下明显,具侵填体,晚材管孔成串径列,弯曲或火焰状,射线细而肉眼下不见为栗属。 各属共同特征,薄壁组织离管带状,似环管(实际为环管管胞),生长轮不同程度波状。     

金丝猴(RHINOPITHECUS)脑的外部形态

本文是对三种金丝猴脑的外部形态的观察结果表明:金丝猴的大脑皮层除存在猴科固有的全部沟裂外,还较其他猴科动物具有更多的副沟。大脑的沟型与疣猴亚科的特征完全吻合,但是很多特点都较叶猴更近似于长臂猿。另外,除了蚓叶和蚓结节较小,四叠体的下丘较猕猴发达以外,金丝猴的小脑和脑干均与猴科的一般特征无明显差异。     

STUDY OF THE VERTICAL AUTOROTATION OF A SINGLEWINGED SAMARA

1. Autorotation of a single-winged samara is a highly nonlinear phenomenon that represents a delicate equilibrium between gravity, inertia and aerodynamic effects. Therefore, in order to analyse this phenomenon, an accurate detailed model is necessary. Such a model has not been presented in the past. Recently the authors derived a detailed model which is briefly described in the paper. 2. The aerodynamic contributions present the most complicated part of the phenomenon. These contributions are treated using the blade-element/momentuin method, with certain improvements and additions. These improvements are necessary due to inherent differences between samara wings and other rotary wing systems (aircraft propellers, helicopter rotors, etc.). 3. The cross-sectional aerodynamics of the samara is characterized by relatively small Reynolds numbers, high angles of attack and rough surfaces. While these characteristics are different from other rotary wings, they are typical of the wing cross-sections of insects and birds. Therefore the lift and drag coefficients, which are necessary for the analysis, are obtained using available data for insect and bird wings. 4. The results of the theoretical model are compared with experimental results of tlvo kinds. The first kind includes results for a samara of an Acer platanoides that were reported in the literature. In addition, a special experimental model of a samiira was built and tested. This model offers a simple way of varying the configuration in order to study (experimentally) the effect of different geometric parameters on the autorotation. 5. In the light of the uncertainty in the aerodynamic coefficients, it can be concluded that there is quite a good agreement between the theoretical and experimental results. Thus, after LTalidation, the theoretical model is used for a parametric study to find the influence of different parameters on the autorotation. The important results of this study are outlined below. 6. The spanwise flolv component and the tangential component of the induced velocity have a very small influence and thus can be neglected. 7. It is important to include in the analysis the effects of the axial induced velocity, the tip effect, and the drag of the root region. 8. Since chordwise variations of the centre of pressure location, as a function of the angle of attack, were seen in the past (based on over simplified analyses) as the mechanism which is responsible for the samara stability, this effect is also added to the model. While the influence of this effect on the pitch angle is large and small on the sinking rate, it results in an increase in the deviation between the theoretical and experimental results. 9. Autorotation is sensitive to the cross-sectional aerodynamic coefficients. This sensitivity is critical since the available data on these coefficients is, to say the least, unsatisfactory and require significant improvement.     

THE LOCATION OF ADENINE NUCLEOTIDE IN THE STRIATED MUSCLE OF THE TOAD

The location of tritiated adenine nucleotide was studied by autoradiography in toad muscle which had been fixed in an acetic acid/ethanol mixture, with lead acetate present to act as the nucleotide precipitant. The muscles were embedded in Araldite. The autoradiographs were examined in both the light microscope and the electron microscope. In confirmation of earlier work, it was found that at least 50 per cent of the adenine nucleotide is concentrated in the I band, near the A-I boundary, and evidence is now available to suggest that this fraction is located in the interfibrillar spaces rather than in the substance of the fibrils. Electron micrographs of unstained sections failed to show any structural features at the site in question, though the triads were made visible by the lead. However, when sections were stained with an alkaline solution containing lead, or with uranyl acetate, "vesicles" were revealed at the appropriate site and it is thought that these may be elements of a transverse network (reticulum) of tubules containing the adenine nucleotide. The location of phosphocreatine could not be investigated because this substance was lost from the muscle during the preparative procedure.     

THE SURGICAL TREATMENT OF HERPETIC KERATITIS

At present, corneal transplantation is the only definitive means of controlling or terminating recurrent or chronic herpetic keratitis. Of 48 keratoplastic operations for various forms of corneal herpes, 16 in quiescent cases and 32 in cases of active keratitis, all but three brought about improvement.Recurrence of keratitis in the graft is particularly likely if the visible lesion is not excised completely and a portion of the graft border lies in contact with diseased tissue.The mode of action of corneal transplantation in improving herpetic keratitis is not clear but several possibilities have been suggested. At least in chronic stromal herpes the removal of diseased and necrotic tissue appears to be a very important factor.     

THE ROUTE OF ENTRY AND LOCALIZATION OF BLOOD PROTEINS IN THE OOCYTES OF SATURNIID MOTHS

The oocytes of saturniid moths take up proteins selectively from the blood. The distribution of blood proteins in the ovary during protein uptake was investigated by staining 2 µ sections of freeze-dried ovaries with fluorescein-labeled antibodies. The results indicate that blood proteins occur primarily in the intercellular spaces of the follicle cell layer, in association with a brush border at the surface of the oocyte, and within the oocyte in the yolk spheres. That proteins derived from the blood are associated with the yolk spheres was confirmed by isolating these bodies and showing that lysis, which can be induced by any of a number of mechanical means, causes them to release immunologically defined proteins known to be derived from the blood. That the level of blood proteins in the cytoplasm is low relatively to that in the yolk spheres was confirmed by the observation that the yellow pigments associated with several blood proteins, although conspicuous in the yolk spheres, are not visible in the translucent layer of centrifuged oocytes. From these and previous physiological observations, it is proposed that blood proteins reach the surface of the oocyte by an intercellular route, that they combine with some component of the brush border, and that they are transformed into yolk spheres by a process akin to pinocytosis.     

THE VISIBLE MIGRATION OF RAPTORS OVER THE MALTESE ISLANDS

Whilst the large migrations of raptors at the Bosphorus and at the Straits of Gibraltar have been documented in some detail, the movements which take place across the Mediterranean itself have been neglected. This paper reports observations of the visible migration of raptors over the Maltese Islands during 1969–73. The largest numbers of raptors were recorded both in spring and autumn during contrary winds or overcast conditions. Normally very few were seen before the early afternoon at either season, in spite of the much shorter minimum sea-crossing in autumn. Large passages occurred in winds with easterly or westerly components. It is therefore concluded that eastward drift does not greatly affect the numbers seen in Malta, as had been suggested by De Lucca (1969); rather that most influxes occurred in the late afternoon during unfavourable meteorological conditions. At other times most migration was probably above the visible range. The number of raptors observed on passage in the Maltese Islands was small compared with movements at the Bosphorus or at Gibraltar. Nevertheless, the numbers of the narrow-winged species (i.e., Ospreys, harriers and falcons) compare favourably with records at the narrow crossings. The only large soaring species commonly seen in Malta was the Honey Buzzard. Evidence is presented which suggests that the volume of Honey Buzzard migration across the central Mediterranean may be much larger than was formerly realized.     

文昌鱼精子的超显微结构

文昌鱼(Branchiostoma belcheri tsingtaoensis)的成熟精子由一个锥形的顶体,头部,颈(被核包裹)和尾部组成。尾可分为中段,主段和末段。微管对复合体为9+2。 文昌鱼精子的超显微结构与前人报道的线粒体由4—6个组成的不同。它由一个大的线粒体围绕尾主轴中段,而且精子属于对称性类型,可以见到核内管,中心粒和致密纤维,终环结构与隐窝位于尾中段与主段之间。本文并对文昌鱼在系统发生中的重要位置和意义作了讨论。     

BURSTING THE BUBBLE: THE SOCIO-CULTURAL CONTEXT OF ECOTOURISM

Ecotourism is a form of tourism that is highly visible and growing rapidly. It is commonly presented and understood as very different from conventional mass tourism because it is especially responsible, and even beneficial, environmentally and socio-culturally. However, such a view may be inaccurate. The favourable image of ecotourism is a consequence of viewing it in an ecotourist bubble, analogous to the idea of the tourist bubble. Within this ecotourist bubble, the destinations and experiences sold to tourists are abstracted from their contexts, thus inducing a distorted image of them and of ecotourism itself. Aspects of what the bubble excludes are illustrated through a consideration of two destinations in the Caribbean.     

STRONTIUM LABELLING OF THE SHELL OF THE ANTARCTIC LIMPET NACELLA CONCINNA (STREBEL, 1908)

Nacella concinna (Strebel, 1908) held in seawater enriched withSr, partially replaced Ca in their shells with Sr The bandslaid down were clearly visible In back-scattered, scanning electronmicroscope images, and such bands could be used to mark carbonateskeletons in field investigations of growth Sr directly replacedCa in the carbonate shells, although not entirely, and newlysecreted shell material always contained less Sr than wouldbe expected from the levels used in treatments. Specimens heldin water with atomic Ca:Sr ratios of 114:1 (control seawater,no added Sr), 4.4:1, 2.2:1 and 1.1.1 produced shell ratios ofca. 635:1, 11.0.1, 3.1:1, and 8.1:1 respectively These valueswere between 1.4 and 7 4 tunes higher than expected, indicatingthat, when shell was laid down Sr was discriminated againstby a factor of around 4. Growth rates were similar before andafter placing specimens in experimental treatments and feedingrates were not significantly different between treatments andcontrols, indicating that the enhanced Sr regimes caused littlestress for the limpets. Limpets were exposed to the experimentaltreatments for 12 days. However, in specimens where growth bandswere visible, it was only possible to distinguish between 5and 8 micro-growth lines. In specimens removed after 3 daysexposure, there was no detectable area of enhanced Sr in theshell. These two observations were interpreted as either meaningthat it takes around 5 days for Sr to enter the extra-pallialfluids which are used for laying down shell, or that the limpetsdid not produce any shell growth during that period. Experimentsplacing Sr in food and not in the treatment water, and vice-versa,suggested that Sr taken directly from the water may be moreimportant than uptake from food. (Received 24 October 1995; accepted 13 December 1995)     

CARCINOMA IN SITU OF THE UTERINE CERVIX—DIAGNOSIS BY BIOPSY

In 50 cases of carcinoma in situ of the cervix uteri, the lesion was present in the cervical canal in 36 instances, but the squamous epithelium of the portio was involved in only 14 cases. Since single biopsy from the portio or external os may show no malignant change even in cases in which vaginal smears are positive for cancer, single biopsy is indicated only in the presence of gross suspicious lesions.When positive smears have been obtained, cold-knife cone biopsy is indicated (a) whenever gross lesions are not visible on the ectocervix, (b) if carcinoma in situ is found in a biopsy of the external os, in order to determine the presence or absence of invasion, and (c) when there are repeated positive smears and biopsy of the portio has not shown the presence of malignancy.The technique of cone biopsy is given in detail.     

THE VISIBILITY AND INVISIBILITY OF PRODUCTION AMONG SENEGALESE CRAFTSMEN

This article examines three social contexts of the production and exchange of craft objects in Senegal. In each context, the extent to which the production of craft items is visible or invisible varies, and these variations in turn affect the ways in which value is construed. These examples are understood as different 'regimes of value' (Appadurai), in whose constitution the production of craft objects, whether this is visible or invisible, plays a crucial role. The argument is that the concept of 'regime of value' needs to address more than simply the 'flow' of commodities, and must have regard for the organization of the relations between production, distribution, and consumption of craft objects. The article also frames these West African examples within a broader argument about the importance of the concept of production in order to redress the over-reliance of contemporary social theories on notions of consumption.