INHERITANCE AND REPRODUCTION 145 



larly at the genesis of every cell-community, and complete 

 parthenogenesis ? 



238. Before we attempt to solve the problem of sex we must 

 study for a space the phenomena of ' inheritance.' When repro- 

 duction is parthenogenetic, offspring reproduce parental characters 

 with variations. When two parents are concerned in reproduction 

 the process is more complicated. In sexually dimorphic species 

 the two parents resemble one another closely in some particulars, 

 for example in blood, muscles, glands, heart, lungs, liver, nerves, 

 and the like. In others, the sexual characters, they differ much 

 more widely. The child, being male or female, develops only one 

 set of the sexual characters. The other set, however, is not 

 wholly absent. Its items are merely rudimentary or latent. The 

 male breasts in man are examples of rudimentary organs. Of 

 latency there is unlimited evidence : for example, female birds 

 have been known in old age to develop the plumage of the 

 opposite sex ; elderly women occasionally develop to some extent 

 beards and moustaches ; haemophilia and colour-blindness, which 

 are usually male characters, are transmitted through daughters to 

 grandsons, and the good milking qualities of cows through sons to 

 granddaughters ; the female characters of bees are apparently 

 transmitted through the drones, and the male characters through 

 the queens ; doubtless, however, both sets of characters are 

 transmitted through both sexes. The male characters of aphides 

 are transmitted through a long series of pathenogenetic females. 

 This form of reproduction, in which one only of two possible 

 characters, or sets of characters, is developed, is termed 

 ' alternative.' 



239. The development (not inheritance, for both sets are 

 ' inherited ' ) of the sexual characters, then, is alternative. But the 

 term * sexual ' must be given a wide meaning. It applies not only 

 to those primary differences of shape and function which are 

 directly concerned in reproduction, but also to those secondary 

 peculiarities of shape, colour, scent, and the like which, being 

 mostly on the surface of the body, and therefore observable, serve 

 as sexual attractions, as well as to the other physical and mental 

 peculiarities which distinguish the sexes. Most of the sexual 

 characters tend to hang together in sets, a male set and a female 

 set ; but some characters, which are sexual in the sense that their 

 function, in whole or part, is to attract the opposite sex, occur in both 

 sexes ; for example in human beings the mane on the scalp and the 

 coloration of the hair, skin, and eyes. But even in the case of those 



10 



