158 THE CASE AGAINST EVOLUTION 



amount of yolk or nutrient material stored up within it. 

 The smaller or male gamete is called a microgamete. It is 

 specialized for the kinetic function, since it contains less yolk 

 and is the more agile of the two. In anisogamy, however, the 

 division of labor is not complete, because both functions are 

 still retained by either gamete, albeit in differing measure. 

 In the heterogamy, the differentiation between the male and 

 female gametes is complete, and they differ from each other 

 in structure as well as size. The larger or female gamete 

 has no motor apparatus and retains only the trophic func- 

 tion. The kinetic function is sacrificed to the task of storing 

 up a food supply for the embryo. Such a gamete is called 

 a hypergamete or egg. The smaller or male gamete is known, 

 in this case, as a hypogamete or sperm. It has a motor 

 apparatus, but no stored-up nutrients, and has even sloughed 

 off most of its cytoplasm, in its exclusive specialization for the 

 motor function. In heterogamy, accordingly, the division 

 of labor is complete. 



We may distinguish two principal kinds of sexual repro- 

 duction, namely: unisexual reproduction and bisexual repro- 

 duction. When a single gamete such as an unfertilized egg 

 gives rise (with, or without, chromosomal reduction) to a new 

 organism, we have unisexual reproduction or parthenogenesis. 

 Parthenogenesis from a reduced egg gives rise to an organism 

 having only the haploid number of chromosomes, as is the 

 case with the drone or male bee, but unreduced eggs give 

 rise to organisms having the diploid number of chromosomes. 

 Parthenogenesis, as we shall see presently, can, in some cases, 

 be induced by artificial means. When reproduction takes place 

 from a zygote or diploid germ cell formed by the union of two 

 gametes, we have what is known as bisexual reproduction or 

 syngamy. It is, perhaps, permissible to distinguish a third 

 or intermediate kind of sexual reproduction, for which we 

 might coin the term autosexual. What we refer to as 

 autosexual reproduction is usually known as autogamy, 

 and occurs when a diploid nucleus is formed in a germ 



