о and 24 hours after moulting. The extirpated glands rinsed in insect Ringer 

 were imj^lanted through an incision at the left side of third abdominal sternite 

 of host specimens narcotized by submerging in water. Unhke Wingglesworth 

 (1936 etc.,) who tried to obtain an increased effect by implanting six or more 

 c. allata contemporaneously, we restrained ourselves to implant only one 

 gland in each case to prevent the possibility of weakening or retarding the hor- 



Table 1 



Effect of с allatum from differently aged nymphs of the 

 5th (last) instar on freshly moulted specimens of the same instar. 



i normal imago 



ip imago with a small area of nymphal cuticle 



na adultoid nymph 



n nymph VI (supernumerary) 



1 — 2 first-second day after moulting, etc. 



i — d freshly moulted imago 



mone production by the implanted glands, which could not be exculded as a 

 result of disturbances caused in the host organism by contemporaneous 

 implantation of a higher amount of heterogeneus tissues. 



Out of the total number of 92 surviving specimens the following result 

 of implantations was obtained: 51 (55,9%) normal imagoes, 9 (9,8%) imagoes 

 лvith small area of nymphal cuticle in the place of implantation, 13 (14,4%) 

 of nymphoid imagoes, 9 (9-8%) of adultoid nymphs, 10 (10-9%) typical nymphs 

 of the Vlth instar (giant nymphs). In total 44- 1 p. с of individuals were treated. 

 The number of experiments excludes the possibility of mistake. The first 

 experiments were made with glands with the adjacent corpora cardiaca. 

 To exclude the possibility that the JH production in the transplanted c, 

 allata might be stimulated by the simultaneously implanted c. cardiaca, 

 in the following experiments we separated carefully and completely с cardiaca 

 and implanted с allata alone. The result was quantitatively the same. 



The question remains in which period c. allata of the last larval instar 

 along with those of the host become capable to produce an effective amount 

 of hormone. To answer it a series of experiments was made in which с allata 

 of individuals in different periods of the last instar (12 — 20 individuals a day) 

 were used for implantation. The results are shown on the table 1. 



154 



