﻿2 6 4 



BOTANICAL GAZETTE 



and outer tissues. No algal zone has been observed in Macrozamia, Zamia, 

 Ceratozamia, and Bowenia, but nodules are produced containing Bacillus 

 radicicola and Azotobader. The author states that the cycads are the only 

 nodule-bearing plants known in which four organisms are in symbiotic relation- 

 ship, namely, two nitrogen-fixing bacteria, an alga, and a cycad. — J. M. C. 



Sexual reactions of mucors.— Blakeslee? has been hybridizing mucors 

 and has secured some interesting results. His (+) and (— ) strains have be- 

 come familiar, and he has shown that the majority of mucors are dioecious. 

 In the experiments presented in this paper he has crossed hermaphroditic 

 species with the sexual races of dioecious forms. It seems that some of these 

 hermaphrodites are heterogamic, showing a constant difference in the size of 

 their gametes, the larger one being presumably female and the smaller one 

 male. A sexual reaction was obtained between the (+) strain of a dioecious 

 mucor and the smaller gamete of the hermaphrodite; and conversely, a similar 

 reaction between the ( — ) strain of the dioecious form and the larger gamete of 

 the hermaphrodite. The conclusion is obvious that the (+) strain of dioecious 

 mucors is female and the (-) strain male.— J. M. C. 



Development of Pyronema.-— Brown 8 has investigated a form of Pyronema 

 confluens, which he calls var. inigneum, in which the trichogyne does not fuse 

 with the antheridium. He finds also that the cultural conditions for the 

 growth of the variety appear to differ from those for the normal form in that 

 sterilization of the substratum is unnecessary. No fusion of nuclei was 

 observed in the ascogonium or ascogenous hyphae, the only one occurring in 



the distinct occurrence of the sex act and its entire absence is a striking illus- 

 tration of the relation between the dependent habit and the sexual apparatus.— 

 J. M. C. 



-Dean* has published a descriptive list of 

 I species having been identified, representing 



Pm m »«. Phvtnrum do). DidcrttM 1.6 >• 



