Dietary Restraint and Control Over “Wanting” Following Consumption of “Forbidden” Food

Eating behavior can be influenced by the rewarding value of food, i.e., “liking” and “wanting.” The objective of this study was to assess in normal‐weight dietary restrained (NR) vs. unrestrained (NU) eaters how rewarding value of food is affected by satiety, and by eating a nonhealthy perceived, dessert‐specific food vs. a healthy perceived, neutral food (chocolate mousse vs. cottage cheese). Subjects (24NR age = 25.0 ± 8.2 years, BMI = 22.3 ± 2.1 kg/m²; 26NU age = 24.8 ± 8.0 years, BMI = 22.1 ± 1.7 kg/m²) came to the university twice, fasted (randomized crossover design). Per test‐session “liking” and “wanting” for 72 items divided in six categories (bread, filling, drinks, dessert, sweets, stationery (placebo)) was measured, before and after consumption of chocolate mousse/cottage cheese, matched for energy content (5.6 kJ/g) and individual daily energy requirements (10%). Chocolate mousse was liked more than cottage cheese (P < 0.05). After consumption of chocolate mousse or cottage cheese, appetite and “liking” vs. placebo were decreased in NR and NU (P < 0.03), whereas “wanting” was only decreased in NR vs. NU (P ≤ 0.01). In NR vs. NU “wanting” was specifically decreased after chocolate mousse vs. cottage cheese; this decrease concerned especially “wanting” for bread and filling (P < 0.05). To conclude, despite similar decreases in appetite and “liking” after a meal in NR and NU, NR decrease “wanting” in contrast to NU. NR decrease “wanting” specifically for a nonhealthy perceived, “delicious,” dessert‐specific food vs. a nutritional identical, yet healthy perceived, slightly less “delicious,” “neutral” food. A healthy perceived food may thus impose greater risk for control of energy intake in NR.     

Brief communication: Reaction to fire by savanna chimpanzees (Pan troglodytes verus) at Fongoli,Senegal: Conceptualization of “fire behavior” and the case for a chimpanzee model

The use and control of fire are uniquely human traits thought to have come about fairly late in the evolution of our lineage, and they are hypothesized to correlate with an increase in intellectual complexity. Given the relatively sophisticated cognitive abilities yet small brain size of living apes compared to humans and even early hominins, observations of wild chimpanzees' reactions to naturally occurring fire can help inform hypotheses about the likely responses of early hominins to fire. We use data on the behavior of savanna chimpanzees (Pan troglodytes verus) at Fongoli, Senegal during two encounters with wildfires to illuminate the similarities between great apes and humans regarding their reaction to fire. Chimpanzees' close relatedness to our lineage makes them phylogenetically relevant to the study of hominid evolution, and the open, hot and dry environment at Fongoli, similar to the savanna mosaic thought to characterize much of hominid evolution, makes these apes ecologically important as a living primate model as well. Chimpanzees at Fongoli calmly monitor wildfires and change their behavior in anticipation of the fire's movement. The ability to conceptualize the “behavior” of fire may be a synapomorphic trait characterizing the human‐chimpanzee clade. If the cognitive underpinnings of fire conceptualization are a primitive hominid trait, hypotheses concerning the origins of the control and use of fire may need revision. We argue that our findings exemplify the importance of using living chimpanzees as models for better understanding human evolution despite recently published suggestions to the contrary. Am J Phys Anthropol, 2010. © 2009 Wiley‐Liss, Inc.     

Dietary responses to fruit scarcity of wild chimpanzees at Bossou,Guinea: Possible implications for ecological importance of tool use

A 13-month ecological study was conducted at Bossou, Guinea, West Africa, to elucidate how a community of wild chimpanzees (Pan troglodytes verus) deals with the scarcity of main foods. During the study period, fruit availability fluctuated radically. The chimpanzees were confirmed to depend heavily on three “keystone resources” which were available when their main foods (fruit pulp) were scarce. These were fruits of Musanga cecropioides, oil-palm (Elaeis guineensis) nuts, and oil-palm pith. These are abundant in the chimpanzees' home range and their nutritional contents compensate for a decrease in nutritional intake from fruit pulp. The presence of these excellent backup foods may explain the high reproductive performance of Bossou chimpanzees. Here, chimpanzees consumed two of the three keystone foods using two types of tool behavior: nut-cracking for oil-palm nuts and pestle-pounding for oil-palm pith. These tool-using behaviors accounted for 31.9% of the total feeding time spent in June (the month in which the highest frequency occurred) and 10.4% in total for the year. It is suggested that the Bossou chimpanzees depend strongly on tools for their subsistence. This implies a possible function for tool technology in the evolution of our human ancestors. Am J Phys Anthropol 106:283–295, 1998. © 1998 Wiley-Liss, Inc.     

Social tradition and the use of tool-composites by wild chimpanzees

Many different kinds of tool use by wild chimpanzees (Pan troglodytes) in their natural habitat have been documented over the last 30 years.¹ Most instances involve the use of a single type of tool for a single task. Even when a chimpanzee uses more than one tool for a single target, the tools usually are used to perform the same function; for example, when the first object employed to perform a task breaks, it is replaced by a similar object. Use of more than one kind of tool for a single task, a tool-composite, by wild chimpanzees (Pan troglydytes) demonstrates high intelligence and motor control which requires foresight, understanding of relations among tools and task, and behavioral coordination. Application of tool-composites has been reported infrequently and may be due to their use in complicated environmental and situational contexts which chimpanzees encounter less frequently throughout their daily activities. © 1997 Wiley-Liss, Inc.     

Dopamine for “Wanting” and Opioids for “Liking”: A Comparison of Obese Adults With and Without Binge Eating

Obesity research suffers from an overinclusion paradigm whereby all participants with a BMI beyond a certain cutoff value (e.g., 30) are typically combined in a single group and compared to those of normal weight. There has been little attempt to identify meaningful subgroups defined by their salient biobehavioral differences. In order to address this limitation, we examined genetic and psychological indicators of hedonic eating in obese adults with (n = 66) and without (n = 70) binge eating disorder (BED). Our analyses focused on dopamine (DA) and opioid genetic markers because of their conjoint association with the functioning of brain reward mechanisms. We targeted three functional polymorphisms related to the D2 receptor (DRD2) gene, as well as the functional A118G polymorphism of the mu‐opioid receptor (OPRM1) gene. We found that significantly more obese controls had the “loss‐of‐function” A1 allele of Taq1A compared to their BED counterparts, whereas the “gain‐of‐function” G allele of A118G occurred with greater frequency in the BED group. A significant gene–gene combination χ² analysis also indicated that of those participants with the gain‐gain genotype (G⁺ and A1), 80% were in the BED group whereas only 35% with the loss‐loss genotype (G^? and A1⁺) were in this group. Finally, BED subjects had significantly higher scores on a self‐report measure of hedonic eating. Our findings suggest that BED is a biologically based subtype of obesity and that the proneness to binge eating may be influenced by a hyper‐reactivity to the hedonic properties of food—a predisposition that is easily exploited in our current environment with its highly visible and easily accessible surfeit of sweet and fatty foods.     

Pestle-pounding behavior of wild chimpanzees at Bossou,Guinea: A newly observed tool-using behavior

A new type of tool-using behavior was observed in a group of wild chimpanzees (Pan troglodytes verus) at Bossou, Guinea. The chimpanzees used the leaf-petiole of oil-palm trees (Elaeis guineensis) as a pounding tool to deepen a hole in the oil-palm crown which appeared after the chimpanzees had pulled out the central young shoots. Finally, the chimpanzees extracted and ate the apical meristem or apical bud of the oil-palm tree which is edible but inaccessible without such tool use. The motor pattern which the chimpanzees employed is similar to that used for termite-nest digging but it is more exaggerated and requires great force. The behavior is reminiscent of pestlepounding. The chimpanzees exploit substantial amounts of food with this tool-using skill, compensating for insufficient fruit foods in the primary forest. This tool-using behavior was first observed in 1990 and, to date, almost half of the group members have been confirmed to use the pestle tool. It appears that this tool-using behavior was invented recently and has since spread widely throughout the group as a habitual one.     

Adoption by captive parturient rhesus macaques: Biological vs. adopted infants and the cost of being a “twin” and rearing “twins”

Four rhesus macaque (Macaca mulatta) mothers each spontaneously adopted and reared an abandoned, unrelated neonate in addition to their own neonate. Data on relative time spent in maternal contact and who maintained proximity were collected for the biological and adopted “twins” and singleton control infants using focal animal sampling. Infant weight gain and the subsequent conception history for each mother were obtained for the following year. Biological infants spent more time in maternal contact than their adopted “twin” siblings. When in contact with their mothers, biological “twins” spent more time in the ventro-ventral position and more ventral time alone than adoptees. Mothers initiated more contacts with their biological infants than their adopted infants, suggesting these differences may be due to differential maternal behavior. “Twins” gained weight at a slower rate than singletons, and mothers rearing “twins” produced significantly fewer offspring the following season. Am. J. Primatol. 43:259–264, 1997. © 1997 Wiley-Liss, Inc.     

Ape-like endocast of “ape-man” Taung

I have identified and illustrated a spherical “dimple” or “depression” on the Taung endocast as indicating the most likely position of the medial end of the lunate sulcus but have not drawn an actual lunate sulcus on Taung because one is not visible. In a recent paper, R.L. Holloway (Am. J. Phys. Anthropol. 77:27–33, 1988) drew a lunate sulcus on his copy of the Taung endocast, incorrectly attributed this sulcus to me, and used it to obtain a ratio of 0.254 to describe “Falk's” position of the lunate sulcus. My published ratio of 0.242 for Taung (Falk: Am. J. Phys. Anthropol. 67:313–315, 1985a) was not considered, although the focus of Holloway's paper was my assessment of the position of the lunate sulcus. Holloway also excluded published ratios for a chimpanzee in my collection from his statistical analysis but, even so, my published ratio for Taung is still only 1.5 standard deviations from his chimpanzee mean. If my chimpanzee brain is included in the sample, the ratio for Taung is 1.2 standard deviations from the mean. Furthermore, one of Holloway's own chimpanzees (B60–7) has a ratio of 0.241, just 0.001 below my ratio for Taung. There is no sulcus where Holloway has drawn one on Taung, his “F(LS)” is not mine, his 2 mm error is not mine, and the correct ratio for my measurement of Tuang is the one that I published, not the one that Holloway attributes to me. Assessment of Holloway's chimpanzee data supports my claim that the dimple on the Taung endocast is within the chimpanzee range for the medial end of the lunate sulcus.     

Using the Tools at Hand: Manual Laterality and Elementary Technology in Cebus spp. and Pan spp.

Cebus and Pan appear to be a remarkable example of evolutionary convergence in behavioral ecology. We examine their apparently analogous solutions to problems posed by laterality of hand function and elementary technology. We scrutinize appropriate published data in a meta-analysis, focusing on Cebus apella and C. capucinus and on Pan paniscus and P. troglodytes. We compare behavioral data in terms of captive versus wild, and tool use versus non-tool use, but notable gaps exist in the data, especially for bonobos. Cebus and Pan spp. are equivalent tool users in captivity, but chimpanzees are notably more extensively so in nature. For hand preference, captive bonobos and wild and captive chimpanzees show ambipreference for non-tool-use patterns. For both Cebus spp. and Pan spp., there is a tendency for individuals to be committed exclusively to one hand or the other for tool use. The data for laterality of hand function fit consistently into the five-level model proposed by McGrew and Marchant (1996).     

Female Coalitions Against Male Aggression in Wild Chimpanzees of the Budongo Forest

In the wild, female chimpanzees (Pan troglodytes) are subject to male aggression that at times can be prolonged or particularly violent. There are no reports of cooperative retaliation to such aggression, a strategy observed in the congeneric Pan paniscus, from the wild despite >4 decades of detailed behavioral study across a number of populations and its occurrence among captive female chimpanzees. If the reports from captivity represent an inherent capacity, then the absence of similar reports from wild populations suggests that females may be able to form coalitions only under appropriate ecological and demographic conditions. During a study of male and female aggressive interactions among chimpanzees of the Budongo Forest, Uganda, wild adult female chimpanzees sometimes formed coalitions with one another to retaliate against male aggression. This may be possible because these females tend to be more gregarious than in other populations of East African chimpanzees, as other studies of the same population have suggested; the extent and variation of female chimpanzee social strategies may, therefore, need reconsideration. Further, my observations strengthen the argument that at least some of the differences between chimpanzees and bonobos may be more of degree than of kind.     

Reproductive Parameters of Female<Emphasis Type="Italic">Pan paniscus</Emphasis> and <Emphasis Type="Italic">P. troglodytes</Emphasis>: Quality versus Quantity

We investigated intra- and interspecific differences in life history and reproductive parameters in bonobos (Pan paniscus) and chimpanzees (Pan troglodytes). We compare the parameters of wild and captive females in order to shed light on the influence of habitat or specific differences or both on reproduction. We present new and additional information on reproductive parameters from captive bonobos and chimpanzees. Captive chimpanzees birth more live offspring and have a shorter interbirth interval, but experience higher infant mortality than captive bonobos. Although captive bonobo females tend to start reproduction at a younger age than chimpanzees, this is effectively only so for wild-born females of both species. Ultimately both species reach the same rate of production of offspring surviving to 5 yr. These results contrast with data from the wild. Wild bonobos tend to have higher reproductive success, a higher fertility rate and a shorter interbirth interval than wild chimpanzees. Reproduction is similar for wild and captive bonobos, which suggests that they are producing at their maximum under both conditions. Overall captive chimpanzees perform better than their wild conspecifics, probably because of lower feeding competition. Infant survival is the only specific difference not affected by captivity. Bonobo infants survive better, which suggests that chimpanzee infants are more at risk. We argue that the interspecific variation in reproductive parameters in captivity is related to the different influence of captivity on reproduction and different pressures of external sources of infant and juvenile mortality.     

Flexible and Persistent Tool-using Strategies in Honey-gathering by Wild Chimpanzees

Several populations of wild chimpanzees use tools to raid bee nests, but preliminary observations of chimpanzees in the Congo Basin indicate that they may have developed sophisticated technical solutions to gather honey that differ from those of apes in other regions. Despite the lack of habituated groups within the range of the central subspecies, there have been several reports of different types of tools used by chimpanzees to open beehives and gather honey. Researchers have observed some of these behaviors (honey dipping) in populations of western and eastern chimpanzees, whereas others (hive pounding) may be limited to this region. Toward evaluating hypotheses of regional tool using patterns, we provide the first repeated direct observations and systematic documentation of tool use in honey-gathering by a population of Pan troglodytes troglodytes. Between 2002 and 2006, we observed 40 episodes of tool use in honey-gathering by chimpanzees in the Goualougo Triangle, Republic of Congo. Pounding was the most common and successful strategy to open beehives. Chimpanzees at this site used several tools in a single tool-using episode and could also attribute multiple functions to a single tool. They exhibited flexibility in responses toward progress in opening a hive and hierarchical structuring of tool sequences. Our results support suggestions of regional tool using traditions in honey-gathering, which could be shaped by variation in bee ecology across the chimpanzee range. Further, we suggest that these chimpanzees may have an enhanced propensity to use tool sets that could be related to other aspects of their tool repertoire. Clearly, there is still much to be learned about the behavioral diversity of chimpanzees residing within the Congo Basin.     

Use of leaves as cushions to sit on wet ground by wild chimpanzees

A new type of tool use, leaf cushion, by wild chimpanzees (Pan troglodytes verus) at Bossou, Guinea, was found. We report two cases: one is indirect evidence; the other is direct observation of a chimpanzee who used the tool. Both cases indicate that chimpanzees used a set of leaves as a cushion while sitting on wet ground. Chimpanzees at Bossou show various kinds of tool use, some of which are unique to the community. Most of these behavioral patterns are subsistence tool use for obtaining food, as at other study sites. The use of leaves as a cushion adds to the few instances of nonsubsistence, elementary technology seen used by wild chimpanzees. Am. J. Primatol. 44:215–220, 1998. © 1998 Wiley-Liss, Inc.     

Do chimpanzees (<Emphasis Type="Italic">Pan troglodytes</Emphasis>) use cleavers and anvils to fracture <Emphasis Type="Italic">Treculia africana</Emphasis> fruits? Preliminary data on a new form of percussive technology

Wild chimpanzees (Pan troglodytes) are renowned for their use of tools in activities ranging from foraging to social interactions. Different populations across Africa vary in their tool use repertoires, giving rise to cultural variation. We report a new type of percussive technology in food processing by chimpanzees in the Nimba Mountains, Guinea: Treculia fracturing. Chimpanzees appear to use stone and wooden “cleavers” as tools, as well as stone outcrop “anvils” as substrate to fracture the large and fibrous fruits of Treculia africana, a rare but prized food source. This newly described form of percussive technology is distinctive, as the apparent aim is not to extract an embedded food item, as is the case in nut cracking, baobab smashing, or pestle pounding, but rather to reduce a large food item to manageably sized pieces. Furthermore, these preliminary data provide the first evidence of chimpanzees using two types of percussive technology for the same purpose.     

Growth of wild and laboratory born chimpanzees

The skeletal remains of a wild juvenile chimpanzee,Pan troglodytes verus, of known chronological age are measured and found to be smaller than laboratory born and fed juveniles of the same age. Other wild born immature skeletal materials of all the three subspecies ofPan troglodytes, including both known and estimated chronological ages, are also smaller than laboratory born chimpanzees when comparisons are made on corresponding age groups. Differences between wild and laboratory born chimpanzees are larger in the limb bones than in the cranium. Limb bones of laboratory individuals grow earlier than those of wild ones regardless of subspecies. Small limb bone size of wild chimpanzees is discussed in terms of life processes.     

Insect-eating by sympatric Lowland gorillas (Gorilla g. gorilla) and chimpanzees (Pan t. troglodytes) in the Lopé Reserve,Gabon

Sympatric populations of lowland gorillas (Gorilla gorilla gorilla) and chimpanzees (Pan troglodytes troglodytes) in the Lopé Reserve in central Gabon consumed insects at similar average frequencies over a 7-year period (30% versus 31% feces contained insect remains). Data came mostly from fecal analysis supplemented by observation and trail evidence. The weaver ant (Oecophylla longinoda) was the species eaten most frequently by both gorillas and chimpanzees. Other species of insects wore eaten but there was virtually no overlap: Chimpanzees used tools to eat Apis bees (and their honey) and two large species of ants; gorillas ate three species of small ants. Thus, despite their shared habitat, the esources utilized were not identical as gorillas do not show the tool-use “technology” of chimpanzees. The frequency of insect-eating by both species of ape varied seasonally and between years but in different ways. This variation did not seem to be related to the ratio of fruit to foliage in their diets. Gorillas of all age-classes ate insects at similar rates. Comparisons with insectivory by other populations of gorillas indicate differences exist. Mountain gorillas (Gorilla g. beringei) in the Virunga Volcanoes, Rwanda, consume thousands of invertebrates daily, eating them inadvertently with handfuls of herbaceous foods but they deliberately ingest insect-foods only rarely. Lowland gorillas at Lopé habitually ate social insects, and their selective processing of herbaceous foods probably minimizes inadvertent consumption of other invertebrates. Gorillas at Belinga in northeastern Gabon, 250 km from Lop6, ate social insects at similar rates but ignored weaver ants in favor of Cubitermes sulcifrons, a small species of termite that occurs at Lopé but was not eaten by gorillas. This indicates that local traditions similar to those reported for chimpanzees also exist amongst populations of gorillas. © 1992 Wiley-Liss, Inc.     

Ant-dipping among the chimpanzees of Bossou,Guinea, and some comparisons with other sites

We present a detailed study of ant‐dipping among the wild chimpanzees (Pan troglodytes verus) of Bossou, in southeastern Guinea, West Africa. Observations suggest a strong influence of prey (Dorylusspp.) characteristics, including aggressiveness and/or gregariousness, on tool length and technique employed by the chimpanzees. Bossou chimpanzees exhibit two ant‐dipping techniques: 1) direct mouthing, and 2) pull‐through. In addition, they were observed dipping for several species of Dorylus ants, classed into two categories: Red and Black. Tool length was longer when dipping in higher‐risk contexts, i.e., at the ants' nest site or on Black ants. The pull‐through technique was almost exclusively associated with dipping at the nest site. This latter technique was associated with tools over 50cm long, whereas direct mouthing was the only technique observed with tools <50cm long. Our experimental findings, together with our observations on the behavior of the chimpanzees, suggest that at the nest, the pull‐through technique was a more efficient technique than direct mouthing. We review our results in the context of ant‐dipping observed at two other long‐term chimpanzee study sites, i.e., Gombe (Tanzania) and Taï (Côte d'Ivoire), where differences in tool length, technique used, and focal Dorylus ant species have been reported. Finally, we urge similar detailed studies of this tool‐use behavior in both Gombe and Taï to shed further light upon our results and their implications. Am. J. Primatol. 58:133–148, 2002. © 2002 Wiley‐Liss, Inc.     

Petite bodies of the “robust” australopithecines

The “robust” australopithecines are often depicted as having large and powerfully built bodies to match their massive masticatory apparatus, but until 1988 the sample of postcranial remains attributed with certainty to this group was very limited. Almost nothing was known about the body of the East African “robust” australopithecine because taxonomic attribution of the postcrania was so uncertain. The body of the South African “robust” australopithecine had to be reconstructed from about a dozen isolated fragments of postcrania. Now a partial skeleton is attributed with confidence to the East African “robust” group along with several isolated bones. The South African sample has more than tripled. Analyses of this vastly expanded sample reveal that a large portion of postcrania attributed to “robust” australopithecines from Swartkrans Member 1 (35%) are from extraordinarily small-bodied individuals similar in size to a modern Pygmy weighing as little as 28 kg. These small elements include parts from the forelimb, spine, and hindlimb. About 22% of these Swartkrans 1 “robust” australopithecines are about the same size as a modern human weighing about 43 kgs and about 43% are larger than this standard but less than or equal to a 54 kg modern human. Approximately the same pattern is true for the Swartkrans 2 hominids, but taxonomic attribution is less certain. All of the Member 3 specimens are similar in size to the 45 kg standard. The partial skeleton of the East African “robust” australopithecine (KNM-ER 1500) has hindlimb joints that would correspond to a modern human of 34 kgs although the actual weight may be 5 to 10 kgs greater judging from shaft robusticity and forelimb size. The largest postcranial element attributed with some certainty to the East African “robust” australopithecine group (the talus, KNM-ER 1464) is about the same overall size as a modern human of 54 kgs, although its tibial facet is slightly smaller. Although many previous studies have hinted at the possibility that “robust” australopithecines had relatively small bodies, the new fossils provide substantial evidence that these creatures ranged from quite small to only moderate in body size relative to modern humans. These were the petite-bodied vegetarian cousins of our ancestors. Sexual dimorphism in body size appears to be greater than that in modern humans, similar to that in Pan, and less than that in Gorilla or Pongo, although such comparisons are of limited value given the small samples, poorly known body proportions, time averaging, and many other problems.     

Responses of wild chimpanzees (<Emphasis Type="Italic">Pan troglodytes schweinfurthii</Emphasis>) toward seismic aftershocks in the Mahale Mountains National Park,Tanzania

This is the first report documenting the responses of wild chimpanzees (Pan troglodytes schweinfurthii) to seismic activities. During our long-term fieldwork in Mahale Mountains National Park, Tanzania, a high-intensity earthquake with a Richter magnitude of 6.8 occurred at 15:19 hours local time on 5 December 2005. During the main tremor, the chimpanzees displayed the “wraa” call, “scream,” and “pant bark” or “bark” vocalizations. Many mild aftershocks followed the main tremor, and the wild chimpanzees displayed a variety of responses to these. In several cases, they climbed trees or stopped activities such as grooming, moving, and feeding. These responses are similar to those previously reported in nonhuman primates. During the observations, a unique behavior, one never reported before was exhibited by a female chimpanzee. She placed her right palm on the ground giving the impression she was inspecting the trembling of the ground.     

THE ULTRASTRUCTURE OF SCENEDESMUS (CHLOROPHYCEAE). I. SPECIES WITH THE “RETICULATE” OR “WARTY” TYPE OF ORNAMENTAL LAYER1

The ultrastructure of the wall layers and ornamentative features of Scenedesmus pannonicus and S. longus are described using carefully correlated freeze-etched replicas, thin sections and scanning electron micrographs. The two species arc enclosed by different types of ornamented layers, S. pannonicus by the tightly filling, “warty” layer and S. longus by the loosely fitting, “reticulate” layer, held off the coenobium by 2 types of tubular propping spikelets and rosettes. The reticulate layer has an intricate substructure, especially when studied with freeze-etching. Its inner and outer surfaces appear different, as is its attachment to the 2 types of spikelets. Whole cells of S. longus subjected to acetolysis lack the cellulose wall and cytoplasm, but all other surface features survive, including the Trilaminar Sheath (TLS); this ornamentation cannot be “pectic.” The cellulose wall and ornamentation is unaffected by boiling water alone. Boiling in 6n NaOH removes the surface ornamentation, but the TLS and wall remain; the possibility that these features contain silica is discussed. The terminal spines of both species consist of closely packed spikelets enclosed within a skin of hexagonally-packed subunits. Similar subunits are seen in the propping spikelets of S. longus, and in the rows or “combs” of laterally fused spikelets of S. pannonicus. The warty layer of S. pannonicus is tightly appressed to the TLS except close to where the cells are joined, where it is suspended free. It is composed of a layer of globular subunits, and small indentations form the warts. Single, evenly distributed warts characterize the freely suspended sections of the warty layer, and the layer that encloses young coenobia soon after they have been formed: in contrast, the warts are clumped over the surface of older and larger colonies. Some of the single warts form characteristic double rows, but these latter remain single even on older cells. The surface structure of the warty layer, TLS, and plasmalemma are revealed by the freeze-etching process.