Blakeslee 



Male and Female Bread Moulds 



139 



as related by A. F. Blakeslee 



Male and Female Bread Moulds 



Reprinted with the permission of the author 

 and pubhsher from Vol. 11, No. 6, News Serv- 

 ice Bulletin, Carnegie Institute of Washing- 

 ton, 1930. 



Sex is a vital phenomenon, almost 

 universal among organisms. The at- 

 tempt, through study of higher organ- 

 isms, to learn what the fundamental 

 difference is between the sexes is com- 

 plicated bv differences in structure. In 

 the moulds, however, the problem can 

 be approached favorably because there 

 are no structural differences apparent 

 between male and female plants to 

 confuse the results. In fact, they can- 

 not be distinguished except by their 

 sexual reactions. 



Indeed, not until this investigation 

 was undertaken, did we learn what the 

 conditions are under which sexual 

 spores (zygospores) in moulds develop. 

 It had been observed that such spores 

 appeared in fungus plates at times but 

 at other times, apparently under like 

 conditions, the moulds failed to pro- 

 duce them. It could be demonstrated 

 that the cultures which produced the 

 zygospores are not single fungus plants 

 but consist of two breeds or strains, in 

 which the filaments from each grow 

 together and fuse. For purposes of iden- 

 tification, these can be called plus and 

 minus strains. 



NATURE OF FUNGI 



The moulds belong to that great 

 group of plants, the fungi, which have 

 no chlorophyll, the green coloring mat- 

 ter, which, in combination with sun- 

 shine, enables many plants to manufac- 

 ture their food. 



Having no chlorophyll, the fungi 

 cannot make the carbohydrate food 

 which they need, the sugars, starches, 

 celluloses, as do green plants, from the 

 water of the soil and the carbon di- 

 oxide of the air. They must obtain their 

 food from food already made so they 

 are dependent plants and live either on 

 dead organic matter or on living or- 

 ganisms. 



It is possible for them to secure 

 their food materials in this manner be- 

 cause they have the power of secreting 

 ferments capable of decomposing the 

 sugars, the starches, the fats, and the 

 other complex substances formed by 

 animals and by chlorophyll-bearing 

 plants. In so doing they play a vital role 

 in the economy of nature for, through 

 the process of decay, for which they are 

 responsible, the chemical elements out 



