42 
g , through want of sufficient space and time wherewith to keep each 
batch of ova separate, I placed all three together. These hatched 
about the same time as did the ova from typical parents, but a greater 
proportion hatched off than of them. Ash was their food as before, but, 
notwithstanding that they had it fresh every day, numbers of the 
larvae died off in the same way as before mentioned. I attribute this 
more to overcrowding than inbreeding, for I had quite twice as many 
larvae feeding together than there were from the typical parents, and 
they continued to die off up till the time of pupation, so that only 60 
finally reached that state. These were early removed from their cocoons 
with the result that in December, 1901, two emergencies occurred, 
both of the form ab. nigra, and the rest emerged in May, 1902. They 
fared rather worse than the preceding batches, for 22 pupae had died, 
but 21 ab. nigra were bred, and eight of the type. Nine cripples also 
emergered, divided as follows—four nigra and five the type. Our 
notice is at once called to the predominance of the ab. nigra form, in 
the breeding of this lot of insects, but that is not surprising, seeing 
that the females in each case were of that form, and we generally 
expect the offspring to bear similarities to the mother, especially when 
so striking an aberration as the one in question is taken into account. 
For example, var. doubledayaria of betularia generally produces a 
good percentage of dark forms when the female is of that form. 
3. The three batches of ova from typical 5 s, after copulation with 
ab. nigra $ s. These were likewise all placed together, as in the case 
with ova from typical parents, only about half of the ova hatched off, 
what the cause was, I could not say, but it is rather peculiar that in 
each case where the female was of the type, only half of the ova laid 
by them should have hatched. Ash was their food as before, and 
there not being so many larvae, they did not die off, like those which I 
have previously mentioned, until nearing the time when they would 
pupate, when one morning, a day or two previous to their going down, 
nearly three parts of them lay dead on top of the cocoanut fibre, fine 
full-fed larvae. What the cause of this was I am not able to answer, 
but whether it was the inbreeding, or some new disease that afflict 
larvae, I do not know, but there they lay dead, and the larvae from 
which I had expected so much only produced 57 pup® when removed 
from their cocoons, but produced a goodly number of ab. nigra, viz., 
34, and 9 of the type and 4 cripples divided as follows—3 ab. 
nigra, and 1 of the type, while 10 did not emerge. This result was 
very satisfying after losing so many of the larvae, for here we get 34 
of the dark form, while of the parents only the $ s were of that form. 
4. The four batches of ova obtained from ab. nigra parents, of 
my experience of breeding this dark aberration of bidentata in 1901, I 
think that which gave the most pleasure was the rearing from the ova 
those obtained from ab. nigra parents. These four batches were like¬ 
wise all placed together, and they hatched off about the same time as 
did the other batches of eggs, nearly all of which hatched. The 
young larv* readily took to ash which was given them, and I think 
there must have been something like 400 lame feeding together, and 
the food they ate was enormous, they requiring food twice a day some¬ 
times, but all these larv® were not to go to the pupal stage, for when 
about half-fed up, they likewise began to die off, first in twos and 
threes, and then in batches, the same unaccountable disease as the 
