192 SUMMARY OF CURRENT RESEARCHES RELATING TO 



P. integrifolia ; an isolated secidium on P. Auricula and nearly related 

 species; and a Micro-Uromyces on P. minima. 



Fungus Diseases of Conifers.* — H. von Schrenk treats in detail of 

 some of the more destructive diseases to which Conifers are liable in 

 New England, the nature of the injuries inflicted, the fungus parasites 

 by which they are caused, and the best remedies. The species of fungus 

 to which special attention is drawn are Polyporus Schweinitzii, P.pinicola, 

 P. sulfureus, P. subacidus, and Trametes Pini, forma Abietis. 



Fungi Parasitic on Green Algse.f — Prof. C. Gobi finds, on Chloro- 

 monas globulosa, a very destructive parasitic fungus, which he describes 

 as a new species under the name Rhizidiomyces ichneumon. The swarm- 

 spores of the parasite settle on both the motile and resting cells of the 

 alga, and establish a connection between their protoplasm and that of the 

 host. Dead and dying filaments of a Vaucheria were found to be attacked 

 by a species of Pythium, P. tenue, chiefly noticeable from the fact that 

 the end of the antheridial filament is not cut off by a distinct wall. 



Variation of Saccharomyces.l — E. C. Hansen gives a succinct re- 

 sume of his previous writings on the variation of Saccharomyces, and 

 deals with the shape of the cells, the formation of spores and budding, 

 the chemical actions, and the variation in brewers' yeast. New obser- 

 vations on asporogenous varieties are also recorded, in the course of 

 which the author goes into the fundamental question whether the varia- 

 tion is due to transformation or selection, and decides in favour of the 

 former, on the ground that it is a general phenomenon always present 

 when the cultivations are made under certain given conditions. 



Cytology of the Gasteromycetes.§ — E. Maire has studied the cyto- 

 logy of this order of fungi, chiefly in the following genera : — Sclero- 

 derma, Geaster, Lycoperdon, Nidularia, Cyathus. In all cases the fusion 

 of two nuclei was observed only in the young basids ; the sub-hymenial 

 cells always contain two nuclei. Many old cells belonging to other 

 tissues contain also a varying number of nuclei, but these are the result 

 of amitotic fragmentation of the two primitive nuclei ; the number of 

 chromosomes was an even number in all the species studied. 



The study of the basids is especially interesting in Scleroderma 

 vulgare. At the commencement of the prophase of the first division, the 

 cytoplasm contains a number of granules stained black by ferric haema- 

 toxylin, round which radiate the microsomes. It would appear that two 

 of these granules become the centrosomes, for a little later two of these 

 only are seen as centres of radiation ; they are then placed one on each 

 side of the nucleus ; the nucleole and the nuclear membrane soon dis- 

 appear, while the chromatic network is transformed into two irregular 

 knotted rods which represent two chromosomes, and which soon stretch 

 from one centrosome to the other. A spindle is at the same time formed 



g* Bull. No. 25 U.S. Deptmt. Agric. (Div. Veg. Phys. and Pathol.), 56 pp., 15 pis., 

 and 3 figs. 



t Script. But. Hort. Univ. Imp. Petropol, xv. (189!)) pp. 211, 251-92. See Bot. 

 Gazette, xxx. (1900) pp. 426, 427. 



t C.R. Trav. Lab. Carlsberg, v. (1900) pp. 1-38 (5 figs.). 



§ Comptes Rendus. cxx:;i. (1900) pp. 1246-8. 



