Endocrine Mechanisms 



755 



onstrated for the hemipteran, Rhodnius;'^^^ the dipterans, Calli'phora,^^^' ^^^ 

 Lucilia,^*- ^^- Sarcophaga,^'^ and Drosophila;^^'^ ' ^^^- ^^'-^ and the orthopterans, 

 Melanoplus,^^-^' ^^^ and Leucophaea.^'-^'' Implantation of corpora allata into 

 allatectomized individuals restores the ability to produce normal eggs. On 

 the other hand, no such relationship appears to exist in the orthopteran, 

 Dixippus,^^^- ^^®' ^-'^ or in Lepidoptera.'^^ Evidence for the humoral nature 

 of this relationship was clearly demonstrated by telobiotic experiments in 

 Rhodniiis, in which the factor concerned was shown to be blood-borne, and 

 by transplantation of the corpora allata into allatectomized individuals, which 

 indicated that the corpora allata exert their typical action irrespective of their 

 new location. ^"^ The influence of the active allatum principle appears to 

 operate through its influence on the deposition of yolk within the eggs 

 rather than on the earlier development of the oocytes. The corpora allata are 



DAYS 



Fig. 285. Rate of increase in ovarian weight in the shrimp, Leander, after: A, eyestalk 

 amputation; B, sinus gland extirpation; G, eyestalk amputation followed by sinus gland 

 implantation. NV, Normal control. From Brown,^ redrawn from Panouse.^ 



apparently essential only throughout the period of oocyte growth and yolk 

 deposition of each successive reproductive cycle. It has been shown that al- 

 latectomy is followed by profound alterations in the general metabolism of 

 Melanoplus}^^ This has led some investigators to support the view that the 

 reproductive functions of the principle from the corpora allata are secondary 

 to more basic metabolic ones. 



Allatectomy also depresses the growth and activity of certain female ac- 

 cessory organs in Calliphora, Melanoplus, and Leticophaea, this influence be- 

 ing independent of the presence of the gonads and hence not operating 

 through them. 



There is considerable evidence that the ovary also exerts an action on the 



