Miscellaneous. 157 



these two herbivorous animals ; a consequence rendered more pro- 

 bable by the fact, that in the dog and the pig, which feed on both 

 animal and vegetable substances, the animalcules are minute, of one 

 or two species only, and not at all numerous. 



DKVELOPMENT AXD PROPAGATION OF SERPENTS. 



The young, on leaving the egg, usually differ from their parents, be- 

 sides their size, by a system of colouring more vivid and more con- 

 trasted, by a head more blunt and more rounded, by the largeness of 

 the eyes, and by the less perfect state of the epidermis and its ap- 

 pendages. They are, however, jirovided with teeth perfectly resem- 

 bling those of the adult, of which they are ready to make use ; and 

 the venomous kinds, instructed by instinct with the power of their 

 weapons, alternately elevate and lower their fangs, and defend them- 

 selves against attacks with that fury which is innate in their race. 

 It was long believed that the tail of the young was shorter in pro- 

 portion to the trunk than in the adult, and that this member pre- 

 sented consequently in them a smaller number of subcaudal plates. 

 If this were the case, we must suppose that new plates develope 

 themselves with age ; but as the number of plates corresponds to the 

 number of vertebrae, we must equally suppose the production of new 

 osseous pieces, as is seen in the Julus, a circumstance little probable 

 in animals so high in the scale of being as those of which we treat. 

 Besides, the researches which I have made on this subject have [iroved 

 the contrary ; since among a great many individuals the young did 

 not show any difterence from the adults in the number of plates but 

 what miglit be considered as accidental. To be sure of the fact, I 

 have repeated these observations on a great number of the most dis- 

 similar species, and have always obtained the same results. 



Shortly after their birth, the young Ophidians undergo their first 

 moult. This operation is repeated in our climate, according to the 

 observations of Lenz, five times in the year, viz. every month from 

 the end of April to the beginning of September ; whence it results, 

 that there is no casting of the skin during the hybernation. It would 

 be very interesting to know how many moults serpents undergo in 

 warm climates, where the state of sleep does not take place. A state 

 of domesticity, a mode of life little natural to these animals, remark- 

 ably influences the functions of the skin, the epidermis of which does 

 not renew itself in fixed and determinate periods ; frequently this 

 operation is very long and so painful that the animal suft'ers much, 

 or it is sometimes followed by death. In order to reject the old epi- 

 dermis, which begins to detach itself at the head, and especially 

 along the borders of the lips, the serpent passes itself through 

 mosses, grasses, or heath, and contrives, by means of slow and con- 

 tinued movements or frictions, to disengage gradually the exterior 

 layer of the skin, which is already replaced below by a new epidermis. 

 The spoils thus removed are found inverted from one end to the 

 other, forming a sac with a reticulated surface more or less diapha- 

 nous, more wide than the body of the snake, because of the dilata- 



