90 SEX AND HEREDITY 



This mode of development continues till the embryo 

 consists of sixty-one cells, of which therefore sixty are 

 without the granules and one contains them. Before 

 the next division of the granule cell, however, the granules 

 instead of concentrating at one pole, scatter through the 

 cell, so that both products of division contain granules, 

 and the embryo has now two granule cells. From these 

 two cells arise the germ-cells of the young Cyclops and 

 therefore eventually the gametes of the adult. They are 

 shown in Fig. 46, K, and again in the much more advanced 

 embryo in Fig. 46, L, where the main features of the fully 

 formed animal (skin, muscles, stomach, etc.) are already 

 apparent. 



We see therefore that in Cyclops the relations of the 

 germ-cells to the body is quite in accordance with the 

 Galton-Weismann view. The body does not manu- 

 facture its gametes as, for instance, it secretes bile or 

 saliva. On the contrary, at the beginning of each new 

 generation the germ-plasm divides into two portions, 

 one (destined to perish) to form the body of the organism, 

 the other to lie dormant, enclosed in the body and fed 

 and protected by it, till the proper time comes for it to 

 break away from it in the form of gametes and continue 

 the stream of life. 



It should perhaps be mentioned that nothing is known 

 of the nature of the granules which thus make visible 

 the distinction between body-plasm and germ-plasm in 

 Cyclops. They are probably unimportant in them- 

 selves, as they have not been observed in other animals, 

 in many of which however the germ-plasm is equally 

 clearly marked out from the body-plasm by other visible 

 characteristics not found in Cyclops. While ignorant of 

 the nature of these various distinguishing marks we can 



