52 THE ZOOLOGIST. 



(Epicrates cenchris), which I brought to the London Zoological 

 Gardens from Brazil about two years ago, as affording an 

 example of the second form of abnormality (for the first is not 

 of so much importance) ; when I was last in England it was 

 desquamating at intervals of about a week, and was miserably 

 thin and exhausted. I have often observed the same thing in 

 snakes whose proper habitat is the palaearctic region when taken 

 into the tropics ; under these circumstances they usually die of 

 marasmus. A River-jack Viper (Vipera rhinoceros) died a short 

 time since at the Gardens, fifteen months after its arrival there, 

 during which lengthy period it neither fed nor shed its skin ; and 

 one not uncommonly sees a snake— especially one not yet 

 habituated to captivity — die suddenly and unaccountably in this 

 state, the body being apparently healthy and well nourished, and 

 the internal organs presenting no trace of disease. 



Is the casting of the cuticle, with its attendant phenoncma, to 

 be looked upon as a mere mechanical process of purification and 

 renewal, or are there other and more important physiological 

 reasons, involving an excretory function necessary for the main- 

 tenance of the reptile's life ? 



To begin with, it hardly seems probable that the simple 

 mechanical inconvenience caused by the presence of the effete 

 membrane which clothes it is sufficient to account for the 

 lethargy and evident general malaise preceding its separation. 

 When we remember that a healthy serpent will contine to feed in 

 spite of severe wounds or other extensive injuries, and its 

 apparent indifference to pain, — moreover, that when the skin 

 has cracked it will take its prey with avidity, even though the 

 flakes are still adherent to it, — we can hardly refuse to entertain 

 the hypothesis that some great vital change in the economy is 

 taking place. From the fact that its retention is fatal, and by 

 itself alone enough to cause death, I believe the exudation of fluid 

 which lubricates the epidermis and renders it easy of removal, 

 to contain some important excretion, the getting rid of which is 

 the primary reason for its being poured out; and that some 

 pathological effect analogous to ummic poisoning or other 

 toxaemia occurs if it fails to be produced. We know that in 

 mammals which transpire by the skin, cessation of the cutaneous 

 action inevitably results in death if prolonged beyond a certain 

 time ; and that if such an animal be varnished, even for no more 



