ILLUSTRATIONS xxiii 



*' 10 ' PACE 



195. Section through the dorsal part of a developing egg of Donacia crassi/"'* 



in order to show the primitive dorsal organ ... . . 247 



196. Diagrams showing the relations sustained to one another by amnion, serosa, 



and embryonic area in three succesive stages of the development ofDoiw<-;<i 

 crassipcs ....... .248 



197. Diagrams to illustrate the formation of the posterior amniotic fold in the 



egg of Donacia crass? 'pcs . . . . . . .219 



198. Two transverse sections through the gastral groove of the egg of Donacia 



crassipcs after it is closed ....... 250 



199. Three surface views of the embryo of Donacia crassipcs at a stage when 



the germinal streak begins to show division into segments . . 251 



200. Longitudinal section through the abdominal appendage of the embryo of 



Donacia crassipes in order to show its glandular character . . 252 



201. Diagram of a longitudinal section parallel to the sagittal plane, but some- 



what lateral, through the embryo of Donacia crassipes in order to show 



the coelomic sacs ........ 254 



202. Sagittal sections through the stomodaeum and proctodaeum of Donacia 



crassipcs . . . . . . . . .255 



203. Diagrammatic representation of mid-gut of the embryo of Donacia crassijjcs 



showing its lateral pouches ...... 255 



204. Two transverse sections through embryos of Donacia, crassipcs of different 



ages, in order to show the modifications undergone by the coelomic sacs . 256 



205. Two diagrammatic sagittal sections through the egg of Periplaneta 



oricntalis in two stages of development ..... 259 



206. The "grub" of Doryphora (Lcptinotarsa} dccemlineata in the third instar, 



from the side ........ 260 



207. Longitudinal section through the embryonic area of an embryo of 



Phyllodromia gcrmanica ....... 263 



208. Transverse sections through three embryos of Phyllodromia gcrmanica at 



three stages of development in order to show the development of the 

 coelomic sacs, the fat body and the generative organs . . . 264 



209. The rudiment of the female genital organs of Phyllodnniun germanica 



reconstructed from sagittal sections ..... 264 



210. Two views of the egg Lepisma saccharina in different states of develop- 



ment ......... 265 



211. Two diagrammatic lateral views through the egg of Machilis altcrnata in 



different stages of development ...... 266 



212. Diagram of the anatomy of the larva of Galcrucclla ulmi . . . 267 



213. Portions of sections through the valve separating stomodaeum from mid- 



gut in the larva of Galcrucclla ulmi ..... 269 



214. Sections of the epithelium of the mid-gut in the pupa of Galcrucclla nlnii 



showing the changes undergone by this tissue at the metamorphosis 



into the adult condition ....... '270 



215. Portions of the Malpighian tubes of a larva and a pupa of Galcrucclla ulmi 270 



216. Portion of the abdominal muscles of the larva of Galcrucclla ulmi under- 



going histolysis ........ 271 



217. Diagrammatic sections through the imaginal disc of a wing in various 



stages of development showing how the wings develop in various groups 



of insects ......... '27'2 



JM8. Two views of the head of the larva of Dijtiscus marcjinalis in two stages 



of development ..... . 273 



219. Longitudinal section through the simple eye of larva of Dijtiscus manjinalis 



parallel to its shortest diameter .... . 274 



