328 PLANT GROWTH SUBSTANCES 



proved to be sexually functional when tested against the appropriate 

 gametes. 



One possible source of error in the foregoing experiments is that 

 the inoculum was from cultures growing in light and that the cells 

 grown in red and in blue light may have contained a small amount of 

 sexual substance because they were but a few cell generations removed 

 from parent cells grown in light. To eliminate this possibility, C. 

 Reinhardi was cultured in darkness and material from the culture used 

 as the inoculum for a new culture grown in darkness. Repetition of this 

 for five successive transfers resulted in cultures in which all cells were 

 undoubtedly hundreds of cell generations removed from a parent cell 

 grown in light. Plus and minus cultures of C. Remhardi grown in darkness 

 through five successive transfers were then exposed under combinations 

 of Corning glass filters giving light of the following wave lengths 



00 o 



4200-4600 A (blue), 5300-5700 A (green), 5900-6400 A (orange), and 



o 



6200-6800 A (red). After exposure for 20 hours the cultures were 

 returned to the dark room and flooded. In all cases the cells became 

 motile in darkness and fused to form zygotes when mixed with functional 

 gametes of the opposite sex. 



The ability of C. Reinhardi to form sexual substances in red, orange, 

 and green light shows that for this species the sexual substances cannot 

 be the combinations of cis- and /raw^-crocetin dimethyl ester that 

 Moewus reports for the eiigametoi group. 



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2. Geitler, L., Biol. Zentr., 51:173 (1931). 



3. JoLLOs, v., ibid., 46:279 (1926). 



4. KuHN, R. and Moewus, P., Ber. dent. Chem. Ges., I},'.^^'] (1940), 



5. , and Jerchel, D., ibid.., 71:1541 (1938). 



6. KuHN, R., Moewus, P., and Wendt, C, ibid., 72:1702 (1939). 



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