BLAKESLEE. — SEXUAL REPRODUCTION IN THE MUCORINEAE. 233 



The zyofospores of this, one of tlie commonest of our moulds, though 

 infrequently reported, can hardly be rare. They are generally covered 

 by the sporangial growth, and to one uqfamiliar with their appearance 

 are distinguishable only with the aid of a microscope. In the fall of 1892 

 Professor Thaxter found zygospores on a spontaneous bread culture 

 which had been started for the class in Cryptogamic Botany. By 

 transferring from the zygosporic region, the production of zygospores 

 was increased, and tlie young sporangia appeared unusual in that they 

 showed a distinct orange-yellow color. This fact suggested that this 

 was a special race or strain, and that zygospore formation might be 

 connected with such strains in which for some reason the sexual ac- 

 tivity had become apparent. The material was preserved dried on bread 

 from year to year, and could be depended on to produce zygospores when 

 pieces of the old culture were transferred to fresh bread, until the spring 

 of 1901, when the sexual activity appeared to have run out. As the 

 " Harvard strain " this was carried to Barnard College by Prof. 11. M. 

 Richards, and to the University of Chicago by Prof. B. M. Davis, and 

 has been used for class work by several laboratories in the country. Pro- 

 fessor Richards has told the writer that his scion of the strain ran out 

 at about the same time with the material in the Harvard Laboratoiy, 

 and the same is true of the material taken to Chicago. 



Coker ('03) reports finding zygospores of this species, and has kindly 

 sent the writer material which came originally from a spontaneous bread 

 culture in the University of North Carolina, Chapel Hill, N. Car. 



Prof. D. H. Campbell has kindly sent the writer zygospore ma- 

 terial which was part of a spontaneous growth on bread exposed in his 

 laboratory at Leland Stanford University, Cal. He writes that he almost 

 always gets zygospores in this way. They were first obtained in 1892 

 from a spontaneous growth on a piece of squash, and every year since 

 he has had them in abundance. 



Zygospores were found in sporangial material from a spontaneous in- 

 fection of sweet potato kindly sent the writer this January ])y Prof. 

 F. L. Stevens, of Raleigh, N. Car. 



Mr. L. A. Scott, of Cambridge, called the writer's attention to a growth 

 of mould on a mixture of miscellaneous vegetables which had been left 

 together for some days in a jar at the Harvard Botanic Gardens. An 

 examination showed that Rhizopus was the principal fungus, and upon a 

 soft spot in an Irish potato a mass of zygospores was found. This po- 

 tato was otherwise unaffected, and zygospores could not be found else- 

 where among the growth. 



