70 METAMORPHOSIS 



be borne in mind that the oenocytes may also perform a significant 

 function in connection with ecdysis. They appear to be gland 

 cells of a specialised type which discharge their secretion into the 

 blood. Furthermore, they show a very marked cycle of secretory 

 activity which synchronises with the process of moulting (Albro, 

 1930 ; Wigglesworth, 1933). Roller (1929) has suggested that 

 they secrete a hormone which induces moulting, but Wigglesworth 

 does not consider that this is likely and is inclined to believe that 

 they are concerned with the synthesis of some of the non-chitinous 

 constituents of the cuticle during ecdysis. 



Although not directly concerned with the metamorphosis, the 

 functions of the corpora allata in adult insects may also be referred 

 to here. Wigglesworth (1936) has shown that these organs are 

 necessary for the production of ripe eggs in Rhodnius. -Further- 

 # more, it was found that the corpora allata of Triatoma females 

 will induce egg-development in Rhodnius. In the absence of the 

 secretion from the corj^ora allata the oocytes continue to grow 

 so long as they are connected with the nurse cells, but when 

 their nutrition is taken over by the follicular cells they die and 

 are absorbed. Further evidence shows that the moulting hormone 

 of the nymphs will not induce egg-development in the adult 

 female ; nor will the egg-forming hormone bring about moulting. 

 In the male the corpora allata are necessary for the full activity 

 of the accessory glands. Their secretion will also induce egg- 

 development in the female and similarly the secretion of the 

 female will activate the male accessory glands. It is noteworthy 

 that Weed (1936) has obtained very similar results with the 

 grasshopper Melanoplus differentialis. By removing the corpora 

 allata, in a series of preliminary experiments, it was concluded 

 that these bodies are necessary for the normal development of the 

 eggs and that, further, secretion in the glandular portion of the 

 oviducts is also influenced by the corpora allata. 



Literature 



Albro, 1930. Journ. MorphoL, L., 527. 

 Berlese, 1913. Redia, IX., 121. 

 BouNHOiL, 1936. C.R. Acad. Sci., CCIII., 388. 

 Caspari and Plagge, 1935. Naiurwiss., XXIIL, 751. 



