SEXUAL REACTIONS BETWEEN MUCORS. QI 



would be possible to label the azygospores of A. spinosa male 

 and female, from their relative size alone, even if one were not 

 subtended by a larger suspensor and surrounded by the out- 

 growths peculiar to the side of the female gamete. Similarly 

 Zygorhynchus may produce male and female azygospores from 

 adjacent gametes that have failed to fuse (Fig. 13). As will be 

 shown later, azygospores may be produced from gametes that 

 have formed as the result of a sexual reaction with a different 

 species. If the opposite gametes of hermaphroditic forms are 

 strictly male and female, it would theoretically be possible to 

 transform a hermaphroditic species into male and female races 

 by germinating its male and female azygospores. This has 

 been attempted ('o6a) and germinations have been obtained of 

 the azygospores of Sporodinia. The mycelia that have thus been 

 obtained produced only a very scanty growth and soon died 

 out before it was possible to test their sexual reaction. Germi- 

 nations of other azygospores, so far as the writer is aware, have 

 never been critically investigated. 



HOMOGAMIC HERMAPHRODITES. 



Spinellus fusiger, Sporodinia grandis two forms found upon 

 fleshy fungi, Mortierella polycephala and Mucor Genevensis 

 are the only homogamic forms definitely known among herma- 

 phroditic Mucors. In none of these is there apparently a con- 

 stant difference in the size of the gametes. Neither Spinellus 

 (which is difficult to cultivate on artificial media) nor Sporo- 

 dinia shows sexual reactions with other species. Mortierella 

 has not been available for study. M. Genevensis, of which the 

 writer has races from four distinct sources as well as derived 

 mutants, shows a strong sexual reaction with both ( + ) and ( ) 

 sexes of dioecious species. The reaction has already been noted 

 ('046, p. 311, pi. IV., fig. 56). Observation on living material 

 shows the reaction to be similar to imperfect hybridization 

 between different dioecious species. The formation of azygo- 

 spores, however, has been observed in different races of this 

 hemaphroditic species as a result of the stimulus of contact with 

 (+) and ( ) strains of Mucor V. Azygospore formation will 

 be further discussed under Absidia spinosa below. 



