EMBRYOLOGY 249 



that a delicate branching coralline, studded with polypi 

 and attached to a submarine rock, should produce, first 

 by budding and then by transverse division, a host of 

 huge floating jelly-fishes; and that these should produce 

 eggs, from which are hatched swimming animalcules, 

 which attach themselves to rocks and become devel- 

 oped into branching corallines; and so on in an end- 

 less cycle. The belief in the essential identity of the 

 process of alternate generation and of ordinary meta- 

 morphosis has been greatly strengthened by Wagner's 

 discovery of the larva or maggot of a fly, namely the 

 Cecidomyia, producing asexually other larvae, and these 

 others, which finally are developed into mature males 

 and females, propagating their kind in the ordinary 

 manner 'by eggs. 



It may be worth notice that when Wagner's remark- 

 able discovery was first announced, I was asked how was 

 it possible to account for the larvse of this fly having 

 acquired the power of asexual reproduction. As long as 

 the case remained unique no answer could be given. 

 But already Grimm has shown that another fly, a Chi- 

 ronomus, reproduces itself in nearly the same manner, 

 and he believes that this occurs frequently in the Order. 

 It is the pupa, and not the larva, of the Chironomus 

 which has this power; and Grimm further shows that 

 this case, to a certain extent, "unites that of the Ceci- 

 domyia with the parthenogenesis of the Coccidae" ; — the 

 term parthenogenesis imphnng that the mature females 

 of the Coccidae are capable of producing fertile eggs 

 without the concourse of the male. Certain animals be- 

 longing to several classes are now known to have the 

 power of ordinary reproduction at an unusually early 



