Ants and Mites 
mites have many hairs and a comparatively large but 
variable cavern. (When we say large, we mean about 
one-sixth of an inch.) 
So the interesting question arises, are the effects of 
mite scratchings and secretions inherited? The forma- 
tion of hairs and the same sort of pocketing of leaf tissue 
is one of the commonest characters of galls, If the 
hairy pockets appear on a young leaf which has never 
seen a mite, then there is an inheritance of these effects. 
There are other cases just as interesting and on which 
a violent controversy has been carried on. The most 
remarkable of all concerns a certain genus of South 
American plants called Tococa, and which lives in the 
Amazon valley. 
The traveller Spruce, forty years ago, wrote an inter- 
esting paper about Tococa, of which he knew at least 
nineteen species in the Amazon valley. These shrubs, 
with one exception, grow in that part of the valley which 
is regularly overflowed for months together by the 
annual inundation of the “white” or silt-laden water. 
They are remarkable for a very curious swollen leaf- 
stalk. This expanded part is hollow and is inhabited 
by fierce ants, which swarm out and bite severely any 
traveller that meddles with the shrubs. Indeed Spruce 
found it very difficult to get satisfactory specimens of 
Tococa in consequence of this bodyguard of ants. He 
points out also that during the annual floods, the ants 
are saved by these hollow residences, which are often 
above the level of the water. 
But the one species which is found outside the in- 
undation level has no such swellings and apparently no 
bodyguard of ants. In the original paper Spruce goes 
on to say that he had occasionally found in several of the 
inundated species leaf-stalks which were not inhabited 
by ants but which nevertheless showed the character- 
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