lg09 ] CURRENT LITERATURE 421 



No two investigators are as yet in accord as to the cytology of the zygospores 

 of the mucors. Gruber, who apparently has done the most careful work on the 

 zygospores of Sporodinia, was unable to find a fusion of nuclei at any stage in their 

 formation or maturation, and several of the most experienced of American and 

 European cytologists of the fungi have personally told the reviewer that they also 

 have investigated the zygospores of this same species, but with no better results. 

 In 1906, Dangeard, working with Mucor fragilis, described the uniting cells as 

 gametangia and saw a fusion of nuclei in pairs soon after the union of the two 

 -exual cells. The condition in Sporodinia was more difficult to follow, but Dan- 

 geard believed he was able to find the same condition in the zygospores of this 

 species. Lendner, in the work before us, criticizes the conclusions of Dangeard, 

 claiming that the figures which Dangeard interprets as stages in fusion are in fact 

 stages in division, since they occur at the same time in the two suspensors as well. 

 What Dangeard considers as degenerating supernumerary nuclei toward the 

 periphery of the zygospore, Lendner never finds in degeneration, and he believes 

 them to be in this position to preside over the formation of the membrane. The 

 real sexual fusion, according to Lendner, is between two large nuclei which ap- 

 proach the center of the zygospore. The two densely staining bodies in the fusing 

 nuclei, which are homologized with chromosomes, give at first four bodies in the 

 fusion nucleus, that eventually are reduced to two and finally unite into a single 



mass. 



germinatio 



zygospores. 



form 



U11ILC JVL.ILJD3 JMIUWCVJ. tllCVL tAiuinui llV v-v V »« _~~ r - 



auction in Sporodinia and many other fungi, the influence of external conditions 

 upon the growth and reproduction of individual species has become a favonte 

 subject of investigation. As the reviewer has shown, external conditions are more 

 influential in determining the form of fructification in the two homothallic species 

 of Sporodinia and Dicranophora, found growing on fleshy fungi, than in the homo- 



Wisn 



a pupil of Raciborski. It seems to be generally true in regard to the influence of 



formatio 

 formation occurs. Wisxiewski 



****- uailUWCl lllctll LI1U3C Wlllllll wiiiv.ii o|7viui» & »«. 



finds that, although under ordinary conditions sporangia are formed togethe 

 with zygospores on the same mycelium, extreme conditions may suppress the 

 production of zygospores, while sporangia are still formed. On pure agar below 

 5° C. and on the same substratum in direct sunlight, only sporangia will be pro- 

 duced. (It may well be the heat rather than the light effect of the direct rays 

 of the sun that is here influential.) Under all other conditions examined, both 

 zygospores and sporangia were produced together, if at all. The decrease in 

 Native abundance of zygospores is associated with a checking of the rapidity ot 

 growth of the mycelium. The transpiration is shown to have no effect upon the 



" Wisniewski, P., Einfluss der ausseren Bedingungen auf die Fruchtform bei 

 Zysorhynchus Moelleri. Bull. Acad. Sci. Cracovie CI. Sci. Math, et Nat. 190H: 



636-68 



2. 



