272 Miscellaneous. 



chorion and from tlio embryo by a thick hiyer of albuminous fluid, 

 is still intact, when tlie little vermiform larva, destitute of any kind 

 of appendages except rudimentary mouth-parts, is already well 

 formed and begins to exhibit movements. At this moment the 

 large flattened cells of the embryonic membrane separate from one 

 another, become free, and assume a globular form ; they undergo a 

 fatty degeneration and float freely, isolated or in little groups, in the 

 liquid which surrounds the embryo. 



When the larva of Smicra emerges it presents almost the same 

 constitution as that of Encyrtus fuscicoUis, recently described by 

 Bugnion* ; it differs from it, however, in its nervous sj'stem, which 

 is formed by a double chain in which the ganglia are sharj^ly 

 distinct and which is in connexion with well-developed supra- 

 ojsophageal centres. It terminates posteriorly in an acuminate 

 extremity, in front of which opens the anus. The hind-gut. which 

 is very short, does not appear to be in communication with the mid- 

 gut, which is filled with a yellowish liquid withoixt any traces of 

 formed elements. 



A large number of embryos of Smicra die before arriving at the 

 limit of their development and undergo a fatty degeneration in the 

 interior of the ovum ; in addition to this the ova are frequently 

 attacked by the mycelium of a fungus, which perforates the chorion 

 and develops in the albuminous liquid. The presence of this fungus 

 does not appear to injure the larva of the Stratiomi/s, the tissues of 

 which remain perfectly healthy. I have never found more than two 

 or three well-developed larva? of Smicra in the same Strationiys- 

 larva. 



The stages which I have so far observed enable me to establish 

 the following facts : — 



In Smicra the segmentation of the ovum is total ; a single 

 embryonic membrane appears at an early period, before the forma- 

 tion of the embryo, by a process very different from that which gives 

 origin to the amnion of other insects. The ovum undergoes a 

 considerable increase in bulk during its development, owing to the 

 remarkable elasticity of its chorion. The embryonic membrane 

 follows the growth of the embryo ; the cells attain large dimensions 

 and do not multiply. When the embryo is well formed the cells of 

 the embryonic membrane separate and enter upon fatty degenera- 

 tion. The ovum borrows from the blood of its host by endosmosis 

 the nutritive materials necessary for its development. Even for a 

 long time after emerging the larva appears to nourish itself only at 

 the expense of the blood of its host. — Comptes Rendus, tome cxiv. 

 no. 3 (January 18, 1892), pp. 133-136. 



* ' Recueil zoologique Suisse,' t. v. (1890). 



