42 



TJie Larva of CJiironounis 



Jnscrtion 

 ol jianselos 



blood-corpuscles, and also to the jjericardial cells and the 

 cells of the fat-body. They are bathed by blood, and he 

 thinks that they probably secrete and 

 discharge into the blood some unknown 

 constituent. 



We are disposed to entertain, though 

 we cannot fully establish, the view 

 held in whole or in part by Weismann. 

 Graber, Wielowiejski, SchJiffer, Ticho- 

 morofif, and Korotnefif, viz. that the 

 blood-corpuscles and oenocytes of in- 

 sects are derived, directly or indirectly, 

 from the ectoderm. With respect to 

 the fat-cells and the pericardial 

 cells, want of evidence prevents us 

 from throwing them into the same 

 group, as Graber and Wielowiejski 

 would do \ 



AVeismann ^ remarks of the larva 

 of Musca that the epidermis is con- 

 tinued beneath the insertion of the 

 muscles of the bod^^'-wall, a necessary 

 j)rovision, it would seem, for the re- 

 newal of the chitinous cuticle without 

 disorganization of the muscles. The 

 same is true of Chironomus (fig. 96). 

 and it is remarkable how little the 

 epidermic cells alter in size or ap- 

 pearance at the places of muscular 

 insertion. It is probable that the 

 remark holds good of Arthropods in 

 o;eneral. 



«7 



Fig. 34. — Nervous 

 sj-stem of yoiing larva. 

 <', first thoracic gan- 

 glion, a', first abdomi- 

 nal ditto, a', seventh 

 abdominal ditto. The 

 connectives still retain 

 their double charac- 

 ter. 



' Graber, Vnher die emhryonale Anlarje den Blut- iind Fdt.gen\hes der Insekien. 

 Biol. CeniraWlalt, Bd. xi, pp. 212-224 (1891}. ^ 1863. 



