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skins the larve are more certainly furnished with the lateral tufts, and the dorsal 
tufts are more certainly of a uniform tint. But a larva in its fourth skin may 
be as mature in these respects as one in its sixth. 
The three first skins therefore seem to be definite and fixed forms—the varia- 
bility in moulting occurs in the later stages. When we come to inquire into the 
significance of this variability, we meet at once with one very decided fact, and 
that is that those that moult only three times always produce male moths; those 
that moult five times always produce females ; those that moult four times 
produce both. 
We may go one step beyond this. The apterous females of 0. Antiqua render ° 
in this instance more than usually marked the circumstance that is usual 
amongst insects, that the female is much larger than the male, from the fact that 
she contains a large number of eggs. There is another circumstance that is also 
usually associated with this fact, and that is that the male emerges from the pupa 
a few days before the female. 
Now, if we take the four moulters, consisting of both males and females, this 
is not so; the females emerge first. But if we associate them in this order— 
{ 3 moulter males 
4 moulter females 
{ 4 moulter males 
5 moulter females 
—we find that the usual rule of the males emerging first is observed. 
This also shows more distinctly that another rule obtains in O. Antiqua ; it is 
one that obtains among bees, and would, I think, be found in other insects, if 
observation on the point were made ; it is this, that the male, though feeding as 
larva a shorter time (being a smaller insect), remains a longer time in the pupa 
state than the female, apparently requiring a longer time to undergo its full 
development. 
It would thus appear that in 0. Antiqua the female moults one time more than 
the male, a circumstance that I have not seen noticed as occurring in any species ; 
and that, further, the moults may vary by one. 
I do not think my observations justify any conclusions as to the circumstances 
governing this last point. 
In a set of larve reared carefully, the 3 male 4 female moulters were fully as 
numerous as the 4 male 5 female moulters ; but in a set reared carelessly, in so far 
that many were kept in one vessel, and their food being taken from different trees 
(always pear) at different times, was sometimes obviously unpalatable, there were 
hardly any 3-4 moulters, but there was a large mortality among these, and it is 
equally possible to conclude that the hard conditions of life killed the 3-4 moulters, 
as that they changed them into 4-5 moulters. 
This point, then, remains for further investigation, and I hope some of the 
younger and more enthusiastic members of the Club will take it up. 
What determines whether or not a larva shall moult the additional time? Is 
it already predetermined before it leaves the egg, or does it depend on conditions 
of weather, feeding, &c.? Would it be possible by selection to raise a race of 
