The feeding and ranging behaviour of Galapagos giant tortoises (Geochehne elephantopus) The Cambridge and London University Galapagos Expeditions, 1972 and 1973

Field observations on the behaviour of adult Galapagos giant tortoises ( Geochehne elephantopus ) on the islands of Santa Cruz (Indefatigable) and Pinzon (Duncan) were made by the 1972 Expedition, and on Santa Cruz by the 1973 Expedition. The animals (in all 14 on Santa Cruz and three on Pinzon) were observed continuously throughout the day for periods of 3–14 days so that their main non-reproductive activities (feeding and walking) could be quantitatively recorded. The period of potential activity was between about 08.00 hrs and 16.00–18.00 hrs, but the pattern of behaviour was extremely variable, both in a given individual and between one individual and another; it seemed little influenced by the relatively slight fluctuations of temperature and climate which occurred during the period of study (July-September) on Santa Cruz. The tortoises on Pinzon, a much more arid island, were less active, and one showed a strongly bimodal activity pattern with a resting period during the middle of the day. The animals studied in 1972 showed a strong disposition to return after several days to the same sleeping place, but this homing tendency was not observed in 1973. This discrepancy can perhaps be attributed to the fact that the two expeditions worked in different areas under different weather conditions. Observations on the plants eaten, on the association between tortoises and certain birds, and on some other aspects of tortoise behaviour such as walking speed and responses to sounds are also described.     

CLEFT PALATE, MICROPHTHALMIA AND OTHER MALFORMATIONS IN EMBRYOS OF LIZARDS AND SNAKES

Six embryos of the eyed lizard ( Lacerta lepida ) with malformations such as short upper jaw, microphthalmia, abnormal fore-brain, cleft palate, absence or deficiency of the pituitary and tail defects are described. Embryos of the common lizard ( Lacerta vivipara ) and adder ( Vipera berus ) with microphthalmia and cleft palate, and of a sand lizard ( Lacerta agilis ) showing partial Siamese twinning are also reported. The aetiology of these malformations, and the well-known occurrence of similar conditions in birds and mammals, is discussed.     

Gastrulation: Is It Analogous to Malignant Invasion

The process of gastrulation has often been compared with thatof malignant invasion. In this paper, the terms "malignant"and "invasion" are denned and the characteristics of malignantcells are discussed. One of the best examples of invasion duringgastrulation takes place during the formation of the endodermin the chick, when the definitive endoblast invades the hypoblast.Experiments are described in which the hypoblast is invadedby a) definitive endoblast, b) other normal embryonic cells,and c) three types of human malignant cells. It was found thatnot only does the hypoblast react differently to normal andmalignant cells, but that the cell interactions differ alsoaccording to the type of malignant cells. In particular, thereare differences in the behaviour of the cells and in the amountof extracellular material laid down between the hypoblast andmalignant cells. It is concluded that even within the limitsof this experiment, chick gastrulation is not wholly analogousto malignant invasion.     

Tail regeneration in the lizards Anguis fragilis and Lacerta dugesii

Rates of tail regeneration in the Madeira wall lizard ( Lacerta dugesii ) and the slow-worm ( Anguis fragilis ) were studied.
L. dugesii regenerates very rapidly, the new tail sometimes attaining a maximum rate of growth of 2'6 mm a day during the fifth week after autotomy. By the twelfth week 90% of the original tail length has been replaced. Average regeneration rates of samples of lizards were reduced after repeated autotomies, but our investigation of this problem was probably complicated by another factor, the amount of tail lost, and is inconclusive.
The tip of the regenerate grows more rapidly than the rest; no elongation occurs at its cranial aspect.
Anguis , even when kept at 27°C, regenerates its tail very slowly, the best performance observed being a new tail of 5 mm after 14 weeks. The longest natural regenerate seen (16 mm) may have taken several years to produce in the wild.
The histological features of regeneration in Anguis are basically similar to those in other lizards. The new osteoderms are formed entirely in the subepidermal tissues but have a regular relationship with the scales. Some nerve fibres are regenerated with the ependymal tube.
The scales on the lizard's regenerating tail develop in a different manner from those in the lizard embryo and show suggestive resemblances to mammalian hairs.     

Canopy-borne seed store in three Western Australian plant communities

The canopy-borne store of seed in the kwongan plant communities at Kulin and Eneabba, and in the forest understorey stratum at Jarrahdale, Western Australia was found to average 1121, 305 and 7 seeds m^-2, respectively. The bradysporous seed reserve of the plant communities increased with decreasing average annual rainfall. In comparisons between species of the same genus, obligatory reseeding bradysporous species tended to have greater numbers of seed per plant than resprouting species. The bradysporous species richness and the average seed content per plant within a species did not vary significantly with soil type, although the bradysporous species composition changed.     

Development of Regenerative Ability in the Lizard, Lacerta vivipara

Among animals which regenerate, it is usually observed thatyounger forms show greater powers than older ones. It becamepossible to investigate this correlation in lizards after thedevelopment of a culturing technique for the eggs of ovoviviparousreptiles (Panigel, 1956). Moffat and Bellairs (1964) amputatedthe tails of lizard embryos at various stages and examined themat hatching. Only the embryos amputated at near-hatching stagesshowed any regeneration. However, subsequent experiments onthe younger stages have shown that most of the embryos becomeconstricted and even amputated by the healing amniotic and allantoicmembranes. This younger group was therefore re-examined forregenerative ability under conditions where the formation ofconstrictions could be controlled. The results showed that smallasymmetrical outgrowths sometimes arise from a fraction of thestump area. These unusual regenerates were never seen to growlonger than one millimeter, or to differentiate cartilage ormuscle. The results suggest that normal regeneration is a processwhich cannot be elicited until a certain degree of maturityof the tail tissues has been attained, and that it is not necessarilybetter in young individuals or in tissues which are less welldifferentiated.