The Organism and its Chemistry 79 



material of the egg (proteins and pliospliorized fats) takes 

 place during development." ^ This statement by Marshall 

 on the authority of Kossel and of Mendel and Leavenworth, 

 may be taken as typifying a wide range of present-day 

 knowledge of the synthesizing power of the growing embryo. 

 Because of its inaccessibility the mammalian ovum has 

 been but little studied chemically. However from what is 

 known of the chemistry of the eggs and embryos of other 

 animals, particularly' of the chick, we are entirely warranted 

 in asserting that a full grown man, for example, contains an 

 enormous number of chemical substances which are not pres- 

 ent in the egg from which he developed. The chondrin of 

 cartilage, the paraglobulin of blood serum, the haemoglobin 

 of red blood corpuscles, the nwosin of striated muscles, the 

 various enzymes of the digestive glands, the neurokeratin 

 and protagon of the central nei'^'ous system, and innumer- 

 able other compounds more or less specific for particular 

 organs and tissues, come into existence in the course of 

 development. And this production of new substances con- 

 tinues, with many organisms at least, up to the very end 

 of the developmental series, even to the end of the lives of 

 the organisms. This is well illustrated by the more or less 

 distinctive oils, essences, acids, etc. occurring in ripe fruit. 

 And few facts bring home more forcibly the subtlety and 

 intricacy of the organism as a producer of chemical sub- 

 stances than do odors and flavors of flowers and fruits. 

 The products of the organism's operations as a manufac- 

 turing chemist are seen to be of two rather shai'ply dis- 

 tinguishable sorts when the total chemical make-up of the 

 developed organism is compared with the total make-up (oi 

 the germ-cells. First there is a considerable number of sub- 

 stances common to adult and germ. Thus both tail and 

 head of the spermatozoa of various fishes were shown by 

 the well known researches of Miescher and Kossel to contain 

 lecithin and cholestrin, both substances occurring also in a 



