284 PROCEEDINGS OF THE AMERICAN ACADEMY. 



AbsidiA CAERULEA Bainier. 

 Mucor Saccardoi Oudemans. 

 Proabsidia Saccardoi (Oud.) Vuillemin. 



This heterothallic species is decidedly common in occurrence, but has 

 been reported in so far as is known by but two observers. Although 

 Bainier's description is given in Saccardo's Sylloge, Vol. IX this fact 

 seems to have escaped the attention of later writers, and one finds no 

 mention of it, for example, in the recent paper of Vuillemin ('03''), in 

 which the genus is considered in some detail and subjected to further 

 subdivision. 



As has already been mentioned under the Citations in Part I, the 

 sporangial condition of this species has been frequently found in this 

 country. The first appearance of its zygospores in the laboratory, how- 

 ever, occurred on an old culture of rabbit dung which the writer had col- 

 lected near Mt. Ktaadn, Me., in the summer of 1902. Less than half 

 a dozen zygospores were found, but by making gross transfers from the 

 region of their formation, their production was increased. Separation 

 cultures, however, made in May, 1903, and contrasts between twelve 

 pure sporangial transfers failed to give the two sexual strains. 



In the following fall an attempt was again made to resolve the fepe- 

 cies into its (-|-) and (— ) strains by obtaining germinations of the hyphae 

 connected with the two suspensors, but the brittle zygosporic branches 

 would not continue their growth when dissected out sufficiently to allow 

 their connections to be followed. By making thirty-eight contrasts be- 

 tween pure sporangial transfers from cultures in which the formation of 

 zygospores was very abundant, four zygosporic lines were finally ob- 

 tained, and, by transfers from either side of these, the two strains were 

 secured. Later tests have demonstrated that thirty-four of the thirty- 

 eight inoculations contrasted were (— ) in character. 



The formation of zygospores in this species seems largely independent 

 of external conditions, and zygospores have been obtained on all the sub- 

 strata tested. In the warm oven at 26°-28° C, the rapidity of growth 

 is increased and zygospores may be secured a day earlier than at the 

 room temperature. 



No marked differences have been observed in morphological charac- 

 ters nor in habit of growth between the (+) and (— ) strains, although 

 they have been carried in separate tube cultures to the thirteenth genera- 

 tion. It frequently happens that the circinate outgrowths arise from 

 one suspensor before they do from the other, or those on one side may 



