372 MONTGOMERY — MORPHOLOGICAL SUPERIORITY. [Oct. 7, 



complex in many cases. Whenever there is intra-parental develop- 

 ment the oviducts become specialized in a portion of their extent 

 as uteri; such structures are not represented in the male. Very 

 frequently also there are special glands for the elaboration of egg 

 envelopes. Very generally there is in the female a more or less 

 complex receptaculum seminis, usually with its peculiar musculature 

 and duct, which is not found in the male. The ovaries may have 

 the same structure as the testes. But not infrequently the ovaries 

 are more complex than the testes, and this is shown particularly in 

 the arthropodous forms. This follows from the necessity of the 

 production of yolk substance for the egg cells, substance to be 

 stored up in the egg for the nourishment of the embryo, whereas 

 such substance is used by the sperm cells only in limited amount- 

 The first formation of the yolk substance is an elaboration by the 

 vitellocytes (nurse or follicle cells), which are germ cells that have 

 lost their reproductive ability and become nutritive. These have 

 their representatives in the testes in the cells of Sertoli, also nutri- 

 tive. But the ovarian vitellocytes play a greater part in the growth 

 of the embryo, and accordingly they are larger or more numerous. 

 Further they are segregated to form particular chambers of the 

 ovary, so that the nutritive and reproductive cells occupy different 

 places within the ovary. This is the case in the Rotatoria and some 

 Crustacea (^Braiichiopoda), and in the Insects, where the egg-tubes 

 that compose each ovary have each a terminal chamber of vitello- 

 cytes {^Hemiptera), or vitellocyte chambers alternating with egg-cell 

 chambers ( Cokopterd). These are all specializations in the arrange- 

 ment of the nurse cells which mark the ovary as being a more com- 

 plex structure than the testis. Then there is found in the female of 

 many Insects an apparatus for oviposition, known as the sting or 

 ovipositor, often of high degree of complication, involving parts of 

 two (or more?) segments; this is entirely absent in the male. The 

 female usually guards and protects the young, sometimes with the 

 development of a brood chamber (some Crustacea) ; that is only 

 exceptionally the case with the male, and sometimes, as in the 

 hemipteron Zattha, he is forced by the female to carry the eggs 

 against his will. But the males of the Pycnogonida carry the 

 young. 



From this rapid survey of some of the facts of sexual dimorphism, 

 we find the supposed excellence of the male to consist in what are 

 mainly unimportant morphological characters, of which the (not 



