312 PLANT GROWTH SUBSTANCES 



of raw filtrates than can be produced with the faciHties commonly 

 available in the academic microbiologist's laboratory. 



Although there are many instances in which control of sexual reactions 

 in fungi by means of hormones or hormone-like substances have been 

 described or indicated, surprisingly little is actually known of the specific 

 roles of such chemical agents. In all too few cases have studies of such 

 effects been carried beyond the initial observations through the intensive 

 explorations requisite to an understanding of the correlative mechanism. 

 Perhaps the information now available from both fungi and algae, 

 although fragmentary and incomplete, may stimulate work in this 

 biologically interesting, and perhaps in time practically important, field 

 of botanical study. 



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5. , ibid., 14:18 (1929). 



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22. , ibid., NS 3:657 (1939). 



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