52 THE CLASS OF INSECTS. 



"germ-ball" essentially agreeing with tlie ovar}-, and the asex- 

 ual larvae begin life as egg-like bodies developed from tils 

 germ-ball, just as eggs are developed in the little tubes of 

 which the ovary is an aggregation. Hence these worms bud 

 out from the germ-stoek, just as we have seen in the case of 

 the Aphides. Leuckart and Wagner farther agi-ee, that " the 

 so-called chorion never being formed in either of them, the 

 vitellus [3'olk] remains without that envelope which has so re- 

 markable and peculiar a development in the true egg of in- 

 sects." .... "The processes of embrj'o-formation agi-ee in 

 all essential points with the ordinarj^ phenomeua of devel- 

 opment in a fecundated egg, exactly' as has been proved (b}' 

 Huxley) to be the case in the Aphides.'" .... "The onl}- 

 difference consists in the germ-chambers of the Cecidomj-ide 

 larvae separating from the germ-stock, and moving about freely 

 in the cavity of the body, whilst in the Aphides they remain 

 permanent^ attached, and constitute an apparatus which, in 

 its form and arrangement, reproduces the conditions of the 

 female organs." 



Thus we can neither pronounce these so-called larvm to be 

 larvae so long as they produce young, neither are they actual 

 males or females ; they are what Leuckart calls asexual forms, 

 which produce false-eggs (pseudova of Huxlej^, as restricted 

 by Leuckart) . This is paralleled by the asexual Aphides, and 

 among Hj-menoptera by the worker Ants, and worker, or, as 

 they were formerly called, neuter Bees, the latter of which have 

 been known to produce j^oung without the interposition of the 

 male ; thus the two sexes, at least the females, are dimorjyhic, 

 i. e. for certain exigencies of life thej' are specialized into two 

 distinct forms, one (as in the asexual ^p/u's) to produce an un- 

 limited number of young during the summer ; the other and 

 sexvial, normal form to produce in the autumn a comparative!}' 

 limited number of eggs. 



Dimorpldsm is intimately connected with agamic reproduc- 

 tion. Thus the asexual Aphis, and the perfect female, may be 

 called dimorphic forms. Or the' perfect female may assume 

 two forms, so much so as to be mistaken for two distinct spe- 

 cies. Thus Cynijys quei'cvs-sj^ongijica occurs in male and female 

 broods in the spring, while the fall brood of females were 



