HORMONAL CONTROL 555 



while the proximal retinal pigment is independent of it (Knowles, 1949-50). 

 So far as the migration of the former is concerned, the most likely hj^jothesis 

 is that pigmentary migration is determined primarily by a dark-adapting 

 and a light -adapting hormone, the production of both being regulated by a 

 nervous centre (in the prawn, Palcemonetes, Brown et al., 1952-53). 



Rej)rodiiCtion in Crustaceans is controlled by hormones differing totally 

 in nature from the chromatophorotropins (Matsumoto, 1951 ; Stephens, 

 1952) and is of considerable ophthalmological interest since, as we have seen,^ 

 the sexual cycle is frequently influenced through the eyes by photo- 

 periodism. In prawns {Leander — Panouse, 1943-46), crabs and crayfish 

 (Brown and Jones, 1947-49), such a hormone inhibits ovarian maturation 

 and oogenesis,while excision of the gland in crabs results in arrested feminiza- 

 tion or increased testicular development (Demeusy and Veillet, 1952 ; 

 Demeusy, 1953 ; Cornubert et al., 1952-53 ; Veillet et al., 1953 ; Cornubert 

 and Demeusy, 1955). 



The control of growth and moulting are similarly determined (Bliss, 1951 ; Havel 

 and Kleinholz, 1951 ; Passano, 1951 ; Stephens, 1955 ; and others), and in association 

 with the moulting cycle there is a hormonal regulation of the metabolism of calcium and 

 phosphorus (Kuntz, 1951 ; Travis, 1951), sugar (Kleinliolz, 1950 ; Scheer and Scheer, 

 1951) and the rate of oxygen consumption (Bliss, 1951 ; Frost et al., 1951). 



THE NEURO-ENDOCRINE SYSTEM OF INSECTS 



The headquarters of the neuro -endocrine system of Insects is a cluster 

 of neuro -secretory cells in the pars intercerebralis of the protocerebrum 

 (Fig. 720) ; their occurrence, discovered first in Hymenoptera by Weyer 

 (1935), has been confirmed in a large number of species,^ and in addition 

 similar groups of cells have been found not only in the cerebral but also in 

 the frontal and the sub-oesophageal as well as in some abdominal ganglia 

 (Day, 1940 ; B. Scharrer, 1941). In relation with these cells, situated on 

 the dorsal aspect of the cerebral ganglion, are two paired gland-like organs, 

 the CORPUS CARDiACUM and the corpus allatum, both closely associated 

 in most insects and m some macroscopically inseparable ; the first is 

 comprised of both nervous and glandular tissue, the second is without nervous 

 components so that they are somewhat analogous to the posterior and 

 anterior lobes of the pituitary body of Vertebrates (Hadorn, 1937 ; Scharrer 

 andHadorn. 1938 ; Vogt. 1942 ; Bodenstein, 1943-44 ; and others). These 

 three components form one neuro -endocrine complex, the corpus cardiacum 

 being linked directly with the cerebral centre by large nerve-trunks carrying 

 neuro -secretory material (Pflugfelder, 1937 ; Hanstrom, 1940 ; Nesbitt, 

 1941 ; Thomsen, 1954). 



The control of integumentary coloration by chromatophorotropins in 



1 p. 16. 



^ Hymenoptera (bees, wasps, ants) — E. and B. Scharrer (1937); Heiniptera (bugs) — 

 Wigglesworth (1939-40) ; Lepidoptera (butterflies) — Day (1940) ; Coleoptera (beetles), 

 Trichoptera (caddis-flies), Diptera (flies) — Day (1940), Vogt (1942), and others. 



