GILBERT M. SMITH 3^3 



each step in degradation of protocrocin is brought about by a different 

 gene and that at least certain steps in the series are each due to a specific 

 enzyme. 



Of the substances produced from protocrocin Moev^-us (cf) identifies 

 the precursor (P) present in a filtrate from cells grown in red light as 

 m-crocetin dimethyl ester, and the end product (E) resulting from 

 illumination of the filtrate with blue Hght as trans-ciocetin dimethyl 

 ester. This identification is based upon the fact that a cis/trans mixture 

 in the same ratio as a P/E mixture also induces sexuahty in cells made 

 motile in darkness. When placed in an ascending series according to 

 intensity' of sexuaUr\' the five sexual types discovered among the euga- 

 metos group show the following range of cis/trans differences (Table 2). 



T.\ELE 2 

 Cis/trans ratios for the five sexual types of the Chlamydomonas 



eugamentos group 



Type Type Type Type Type 



12345 



For female cells differences in the cis/trans ratios of the five sexual 

 types approximate ven.' closely the ratios in the Bergmann -Niemann 

 series of (2:1), (2:3), (2x3:1), (2x3^:1), (2x3':!;, (2x3*:!), ar. : : .- r. .t 

 cells they approximate the trans/ cis ratios (see Table 3). 



Since cis/ tram mixtures induce sexuahty in darkness it might be 

 argued that these are the only substances concerned with gametic 

 union. Moewus (12) holds that this is not the case and that there are 

 both gamete-attracting substances ''^amones) and sex-determining sub- 

 stances ftermonesj. He holds that cis trans mixtures are ganK>nes and 

 that picrocrocin and safranol are termones. The gamone (g^-'nogamone) 

 of a female cell alwavs contains more cis- than /razij-crocetia dimethvl 

 ester, whereas the reverse is true for the gamone (androgamone) of a 

 male cell. 



To prove that cis, trans mixtures (gamones) are not the only substances 

 concerned in sexuaht}', Moewus (12) took a filtrate from a heterothallic 



