434 HOMEK WHEELON 



male sea-stickelback of weeds bound together with threads derived from 

 the kidneys, the development of the specialized arm of the octopus used 

 in the transmission of the spermatophores into the mantle chamber of the 

 female 1 , the peculiar activity of the salivary glands in swiftlets and croco- 

 diles, and the periodic activity of the anal gland of snakes and the cloacal 

 glands of the tortoise and other reptiles. All characters of this type either 

 aid in the processes of mating or enable the sexes more easily to detect 

 each other. 



HI. Nonreproductive Tissue in relation to Sex 



1. Relationship Between the Testes and the Male Secondary Sexual 

 Characters. Relation of the Testes to Sex Characters in Insects. 

 Whether or not the sex glands affect the sexual instincts and secondary 

 sexual characters depends upon the forms of life selected for study. For 

 instance Oudemans, Meisenheimer, and Kellog have shown that the repro- 

 ductive tissue of insects in general appears to have no influence whatever 

 upon the development of sexual characters, although sex dimorphism is 

 well marked. The removal of the ovaries and testes from the caterpillars 

 of gipsy moths in no way alters the development of sexual differences. 

 Furthermore, castrated female caterpillars into which the sex glands of 

 young males have been grafted develop into characteristic female moths. 

 Castrated male caterpillars carrying ovarian transplants develop into 

 chrysilids, and finally into moths. These moths show no characteristics 

 whatever of the female. Dissection of the fully grown moths demonstrates 

 that the ovaries have formed many connections with the outlets of the 

 male organs left behind (Kopec (a) (6)). Testes grafted into female bod- 

 ies develop and produce spermatozoa (Fig. 1). Crampton has further 

 shown that transplanted heads of the opposite sex develop in accordance 

 with their original sex. Such striking observations show clearly that, in 

 these species at least, the reproductive tissue of either sex will develop in the 

 body of the opposite sex without in any way influencing the secondary 

 sexual characters of the individual. It is necessary, therefore, to study 

 these characters apart from the influence of the sex glands. 



Certain insects, however, do show morphological and instinct changes 

 following gonadectomy, but such changes do not appear to result directly 

 because of the loss of the gonads. For instance, Kornhauser has shown 

 that male Thelia, bimaculata parasitized by dryinid Aphelopus theliae 

 assume the pigmentation of the female and increase in size. Also small 

 spines on the abdominal sclerites take on the arrangement characteristic 

 of the female. The genital appendages are reduced but never changed 

 into those of the opposite sex. Nevertheless, a normal testis with sperm- 

 atozoa may be present in parasitized males showing changes toward the 

 female type and a perfect female soma may be associated with a normal 



