220 A. G. HAMILTON. 
cattle cannot be kept domesticated, much less run wild, through 
the bites of a small fly. 
Again, the effect of the presence or absence of certain mammals 
on the vegetation is well shown in the oft-quoted fact—(before 
referred to) that the success of red clover in seed-bearing, depends 
largely on the presence of cats in the neighbourhood, which keep 
the field-mice down, and so allow the humble-bees to increase, 
(the latter being preyed on by field-mice) and as humble-bees are 
supposed to be indispensable to the fertilisation of the red clover, 
the yield of seed would naturally increase with the presence of 
eats. For this reason humble-bees were acclimatised in New 
Zealand, and the red clover has become thoroughly naturalized 
there; attempts are being made to bring about the same state 
of affairs in New South Wales by importing the humble-bee from 
New Zealand. I have seen, however, that red clover is quite fertile 
at Mt. Wilson in the Blue Mountains, and is spreading there 
rapidly. My friend Mr. J. D. Cox, called my attention to the 
fact that every head was full of seed, which shows that either the 
plant has learned to fertilise itself in its new habitat, or that some 
suitable insect has found it out. This latter I am disposed to 
think the true state of the case from the fact that it so uniformly 
produces seed and that it has only recently been introduced there. 
We were not able, however, to discover any insect actually at work 
on it. On mentioning this fact to Mr. F. Turner, Botanist to the 
Agricultural Department, he informed me that he knew of the 
plant seeding in other localities of New South Wales. 
(b) Indirect modification of the native fauna and tts effects on 
the flora. 
A good deal of the foregoing applies to this heading also. The 
destruction or protection of one group of animals has a correspond- 
ing effect on other groups, and from them it is transmitted to 
the flora. For example, the destruction of birds of prey, and 
dingoes has caused a great increase in the numbers of some of the 
smaller marsupials, ¢.g., opossums and bandicoots. These latter 
in the neighbourhood of farms do much damage to potatoes and 
