498 ON THE FEMORAL ULAND OF '^ RXITIIORHYSCHUS, 



Jive thousand times as virulent as our preparation of platypus 

 poison, and the above comparison only obtains between platypus 

 poison and snake venom diluted to this extent. 



At the conclusion of our survey of the literature of this suljject, 

 we pronounced the opinion that as far as the evidence adduced 

 went, it presented a very strong case in favour of the contention 

 that these glands, at any rate at some seasons, produce a poisonous 

 secretion. 



We venture to think that the results of our experiments have 

 established the fact that the secretion is poisonous at some time 

 of the year. Whether the animal is capable of discharging a 

 secretion possessed of poisonous properties at all seasons of the 

 year is not at present determined. Creighton* states definitely 

 that the gland is subject to seasonal variations in size just as is 

 the case with the mammary gland and testes (Bennett). We have 

 been unable to find on what evidence Creighton makes this 

 statement; but the differences in minute structure observed l)y us 

 lend support to this view. 



The idea naturally occurs to one that this apparatus, which is 

 confined to the male sex, owes its peculiar development to the 

 operation of sexual selection. That it is a weapon used by the 

 males on one another when conflicting for the possession of the 

 females, is an idea which would become extremely probable if it 

 could be established that the gland is specially developed at or 

 about the. pairing season. This is a point which could be settled 

 without difficulty provided specimens could be obtained in sufficient 

 number at suitable periods of the year, say August and February. 



Bennett found developing ova in the uterus as early as Septem- 

 ber, so that in all probability the animals pair during the latter 

 part of August and earlier part of September. 



That the secretion obtained by us from the glands of an animal 

 killed in June proved actively poisonous, whilst that from an 

 animal killed in April was innocuous, is interesting in this respect, 



* Loc. ('it. 



