26 STRUGGLE AMONGST ANIMALS 



has a larger brain and a robuster constitution, and is 

 almost as adaptable and intelligent as the common 

 domestic dog. It thrives in captivity, and becomes 

 tame and friendly. The thylacine, like many crea- 

 tures of low intelligence, remains fierce and shy in 

 captivity, hardly learns to distinguish between its 

 keepers and casual visitors, and is much more liable 

 to disease. There is no particle of evidence that the 

 dingo made any direct attack on the thylacine. If 

 a struggle for existence did take place between the. 

 two animals, it was a struggle in which we must 

 suppose the energies of each to have been directed 

 against the environment common to both, rather 

 than directly against each other. Each sought food 

 of a similar kind, each had to resist the inequalities 

 of climate, to find water, to produce and to rear 

 young. What the deciding factor was, is impossible 

 to say. It may have been a question of resistance 

 to disease. Marsupials in captivity, and probably 

 in nature, are subject to the attack of a parasitic 

 fungus producing in their tissues a very fatal disease 

 known as mycosis, a disease that happens to be 

 much more common among birds than among 

 mammals. This disease is practically unknown among 

 dogs and wolves, but it has killed at least one of the 

 few thylacines we have possessed at the Zoological 

 Gardens. 



Although we do not know, we can at least infer 

 that the struggle in which the thylacines perished in 

 Australia and the dingo succeeded, was one in which 

 success came to the hardier, larger-brained and more 

 adaptable, rather than to the better armed and more 

 aggressive creature. A struggle, in fact, much more 



