122 THE CANADIAN ENTOMOLOGISY. 
upon this point, a solitary winged specimen was secured and confined ina 
box in which a sprig of the insect’s natural food had been previously 
placed to satisfy its wants ; due examination having been made to the 
intent that nothing in the shape of food or animal life should stand in 
the way of a fair and impartial test. After the lapse of twenty-four: 
hours, the inside of the box and its contents were examined with a glass. 
of moderate diameter, and a single, newly-born Aphis was discovered 
fastened to a leaf stalk, in the act of imbibing its juice. 
A further continuance of the feeding process for several days longer 
was productive of the same positive results. The rate of increase in this 
species, as shown by these experiments, unlke its European congeners, 
was proved to be but one a day; so it is to be seen that the insect does. 
not propagate as rapidly in this case at any rate, as naturalists have 
asserted. European species, we read, produce at the rate of three, four, 
and seven a day, according to eminent authorities. As our native Ameri- 
can species differ in many points from European, in a structural as well as 
a functional sense, this difference in the rate of propagation may not be 
wondered at. From the above facts it does seem that nature has decreed 
that there shall be both winged and wingless specimens in the spring time, 
for it seems just to conclude that both varieties are virgin females. But 
other observations which were subsequently made, seem to foreshadow 
the existence of males also; but the evidence upon this point is not of 
the most positive character, and requires further facts to settle it beyond 
the shadow of a doubt. 
Having secured similar winged specimens a few days later, they were 
submitted to a like test, when both positive and negative results were 
reached. Here was a rather curious and interesting problem for solution. 
Why some should prove fertile, and others, which in no single particular 
differed therefrom, so far as could be determined, should manifest a 
contrary state of affairs was more than could be divined, and this too after 
frequent experiments had been made. If the latter are males, as their 
sterility would seem to indicate, the solution is selfevident ; but if of the 
opposite sex, there can be no adequate key to unlock the problem, unless. 
the principle of excessive nutrition, which seems to account for so many 
strange things in the vegetable creation, should prove to be it. But even 
here a doubt arises, as observation has shown me that a succulent shoot 
produces almost invariably wingless specimens, while a less tender one the 
opposite variety. As the very existence of the two forms depends upon 
