36S MONTGOMERY — MORPHOLOGICAL SUPERIORITY. [Oct. 7, 



the condition known as Neotenia. This term is applied when the 

 germ cells mature before the tissue cells have attained their final 

 specialization; the individual is mature sexually before it is corpo- 

 really. Neotenia is found mostly (whether always, I cannot say) 

 in males. It is not infrequent, particularly among parasites ; thus 

 in the male Gordiacean the spermatozoa may be fully mature before 

 the animal's external enticula is completely developed. This is 

 but another case of the.male condition, i.e., the essentially mascu- 

 line characteristic, appearing earlier, at a more embryonic stage, 

 than the female state appears. An increasing acceleration (in the 

 sense of Cope) of neotenia would throw the male condition further 

 back into the ontogeny, and could lead to the formation of embry- 

 onic males, such as in the Rotatoria, etc. 



There next comes up for consideration an array of forms where 

 there are no well-marked secondary sexual differences, i.e., differ- 

 ences apart from those furnished by the reproductive systems, and 

 where the sexes are separate. These are found mostly in the lower 

 hivertebraia ; mo^i Nemertini iy^ni Carinella vf\i\\ distinct colora- 

 tion of the sexes), most Hydrozoa, Scyphomedusce, Echinodermata, 

 Enieropneusta, most dioecious Mollusca and Annelida. Absence of 

 secondary sexual differences is here correlated with aquatic life, 

 fertilization of the germ cells without copulation, and relative sim- 

 plicity of the genitalia. The latter in each sex consists of gonads, 

 regions of localization of the germ cells known as testes and 

 ovaries, and comparatively simple efferent ducts (or no preformed 

 ducts). Accordingly, the testes and ovaries may be essentially 

 alike, as simple sacs, in the Hydrozoa and Neniertini, or surfaces in 

 the Polychceta. When this is the case, and in the absence of sec- 

 ondary sexual differences, we cannot say which sex is morphologi- 

 cally the more advanced ; but there is no evidence that the male is 

 the superior. In the dioecious Mollusca the reproductive organs of 

 the female are the more complex, in the presence of various glands 

 concerned with the formation of ^gg envelopes, so that in these 

 forms the female is the more perfect. 



In the large groups of Nematoda, Gordiacea, Crustacea, Ara- 

 chnida, Insecta, progoniate and opisthogoniate Myriapoda, there 

 are generally present secondary sexual differences as well as differ- 

 ences in the genitalia. In the Gordiacea the male is smaller than 

 the female, and sometimes with greater specialization of the cuticu- 

 lar protuberances ; but the female has more complex reproductive 



