248 PROCEEDINGS OF THE AMERICAN ACADEMY. 



the sporangia in these last cultures must be produced from the same hyphae 

 that were connected with the zygospores, yet of five sporangial transfers 

 from these only one gave rise to zygospores, although the conditions of 

 nutrient, temperature, and moisture, were identical. This tube, more- 

 over, furnished no clue to a solution of the problem, since ten pure trans- 

 fers from it to a variety of favorable substrata failed to produce anything 

 but sporangia. On the original assumption that zygospore formation was 

 characteristic of certain strains this fact seemed to indicate that the sex- 

 ual character was not distributed throughout the mycelium, but was handed 

 on through the spores of only a part of the sporangia. All attempts, 

 however, to locate these favored sporangia by taking transfers from the 

 lower part of the cultures near the zygospores were as fruitless as were 

 transfers from sporangia higher up. Yet whenever a mass of the spo- 

 rangia froin a zygosporic culture even without the zygospores was trans- 

 ferred, zygospores invariably developed. 



TABLE I. 



Substratum. Results, 



Egg (yolk) sporangia; zygospores scattered. 



Cocoanut sporangia ; zygospores abundant. 



Potato infected with bacteria. 



Apple sporangia scanty ; one zygospore. 



Banana sporangia ; no zygospores. 



Orange sporangia ; no zygospores. 



Horse dung sporangia; zygospores scattered. 



Milk in sponge sporangia ; zygospores abundant. 



Urine in sponge no growth. 



Cocoanut milk in sponge sporangia scanty ; zygospores scattered. 



Milk in test-tube sporangial growth 1.5cm. high; no zygospores. 



Urine in test-tube no growth. 



Cocoanut milk in test-tube sporangial growth 2.5 cm. ; zygospores abun- 

 dant. 



Decoction of banana in test-tube sporangial growth 0.5 cm. ; no zygospores. 



Decoction of prune in test-tube sporangial growth 0.5 cm. ; no zygospores. 



From Petri dish separation cultures which were made to determine 

 whether zygospores could develop from a single spore, separate mycelial 

 " colonies " were transferred to suitable nutrients in tube cultures and 

 in all cases only sporangia resulted, although scattered zygospores oc- 

 curred in some of the Petri dishes after the various colonies had become 

 indiscriminately mingled. Our present knowledge shows that in those 

 few cases in which transfers from a single sporangium developed zygo- 

 spores, a contamination of sporangial spores from an opposing strain must 

 in some way have taken place. 



