385 



\n regard to the last, or terminal brood, in the autumn, invest- 

 igations made within a few weeks, as these insects were closing 

 up their economy for the year, showed results somewhat different 

 from those recorded in science ; for, instead of this last brood 

 being composed of males and females, I found, upon an examina- 

 tion by the microscope, of the internal organs, that this brood 

 contained, also, individuals like those of the preceding brood, — 

 that is, without sex, but capable of reproducing their kind. 



The conditions, therefore, which determine the appearance of 

 distinct male and female individuals in this last brood, do not 

 seem referable to the fact of its being the last, but rather, per- 

 haps, to relations of nutrition we do not now understand. 



With these data, the question arises, what is the proper inter- 

 pretation to be put upon these reproductive phenomena we have 

 just described .? My answer would be, that the whole constitutes 

 only a rather anomalous form of gemmiparity ; they are not 

 females, for they have no female organs ; they are simply 

 gemmiparous animals, and the budding is internal, instead of 

 external, as with the Polypi and Acalephce ; moreover, this 

 budding takes on some of the morphological peculiarities of 

 oviparity ; but these peculiarities are economical and extrinsic, 

 and do not touch the intrinsic nature of the processes therein 

 concerned. Viewed in this way, the different broods or colonies 

 of AphididoB cannot be said to constitute as many true genera- 

 tions, any more than the different branches of a tree can be said 

 to constitute as many trees ; on the other hand, the whole suite, 

 from the first to the last, constitute but a single true generation. 

 I would insist upon this point, as illustrative of the distinction to 

 be drawn between sexual and gemmiparous reproduction. Mor- 

 phologically, these two forms of reproduction have, it is true, 

 many points of close resemblance, but there is a grand physiolo- 

 gical difference, the perception of which is deeply connected 

 with our highest appreciation of individual animal life. 



A true generation must be regarded as resulting only from 

 the conjugation of two opposite sexes, — from a sexual process in 

 which the potential representatives (spermatic particle and ovum) 

 of two opposite sexes are united for the elimination of one 

 germ. The germ power thus formed may be extended by gem- 



PROCEEDINGS B. S. N. H. 25 APRIL, 1854. 



