ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 623 



Peronosporineae, and proceeds to examine the statement that there is a 

 reduction of chromatin substance before fertilization. He describes his 

 working methods, and gives a full account of his research of the two fungi, 

 more particularly of Albugo Candida. He found that in the develop- 

 ment of the sexual organs of both forms there was only one nuclear 

 division that differed in any way from the typical karyokinesis, and the 

 nuclei resulting from this division, both male and female, have the same 

 number of chromosomes as the vegetative nucleus. The two gamete- 

 nuclei lie together for some time before fusing to form the primary 

 oospore nucleus. This zygote nucleus differs from all the others in the 

 amount of chromatin it contains. After a certain time, when certain 

 changes of structure have taken place, division occurs : the spindle 

 of this division is much longer than those of the other divisions, and the 

 arrangement of the chromosomes on the equatorial plate is much looser. 

 At the ends of the spindle are small, dark bodies, probably centrosomes. 

 The division may be considered as heterotypic. The daughter-nuclei of 

 the zygote nucleus undergo simultaneous division, and the number of 

 chromosomes was about sixteen ; those of the zygote nucleus were more, 

 but their number could not be accurately determined owing to the 

 structure of the nucleus, and the difficulty in obtaining good preparations 

 of that stage. 



"to v 



Vine Roesleria.* — Roesleria of the vine is due to a fungus, Vibrissea 

 hypogsea, an Ascomycete parasitic on the roots. P. Yiala and P. Pacottet 

 have cultivated the spores of the fungus in solids and fluids, and have 

 reproduced the conidial stages. On the solid media were formed thick 

 layers of green mycelium and numerous conidiophores. On the liquid 

 cultures they obtained the same green mycelium, with spongy spherical 

 bodies formed in the liquid, on the exterior of which were numerous 

 tubes, some of them swollen in a succession of balls. These balls be- 

 came finally green spores. 



Trochila Populorum.f — C. W. Edgerton has been making cultures 

 of this fungus, to try and link it up with Marssonia castagnei, Potebnia 

 having hazarded the opinion that the two fungi were life-stages of the 

 same species. Both grow on poplars. Edgerton has not been wholly 

 successful, but he found a Trochila always growing on Marssonia spots, 

 which he diagnosed as T. Populorum. He gives a minute description 

 of the fungus. 



Studies in Pyrophilous Fungi. } — It has been a debated question as 

 to the reason why certain fungi, such as Pyronema, only grow on burnt 

 soil. F. J. Seaver and E. D. Clark have examined the soils chemically, 

 and have compared the heated with the unheated. They have come to 

 quite definite conclusions as to the value of the heating process ; they 

 find that heat renders soluble a great amount of material in the soil, and 

 thus makes it available as food for fungi. They tested their results in 

 various ways, and a full account is given of the various experiments. 

 Soil subjected either to steam or dry heat (either in a closed oven or by 



* Comptes Rendus, cl. (1910) pp. 1770-1. 

 t Mycologia, ii. (1910) pp. 169-73 (7 figs.) 

 X Tom. cit., pp. 109-24 (3 pis.). 



