ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 473 



Sclerotinia Crataegi.* — P. Magnus describes the entire development 

 of this fungus, which in the Man ilia stage attacks and mummifies the 

 fruits of .the hawthorn and also destroys the leaves. Sclerotia thus 

 arising from the fruit were kept in suitable conditions, and the Peziza 

 fruit was formed. On the same sclerotia there grew layers of conidio- 

 phores which bud off at the apex rows of small globose conidia. This is 

 the microspore form that has been described for other Sclerotinia. The 

 ascospores differ from others of the genus in the apiculate ends. A 

 comparison is drawn between various Sclerotinia species as regards their 

 life history and spore formation. 



Cytological Researches on some Ascomycetes.f — Rene Maire, in 

 a few words, states the present extent of our knowledge of nuclear fusion 

 and nuclear division in the Ascomycetes, quoting the work of Dangeard, 

 Harper, Barker, Guillermond, and others, and then proceeds to give the 

 result of his own research on the subject. He is occupied chiefly with 

 the behaviour of the nuclei in the ascus. He has worked over a number 

 of species, Galactinia succosa, Acetabula acetabulum, Pustular ia vesiculosa, 

 and species of Morchella, Rhytisma, Hypomyces, and two Lichens, Pelti- 

 yera canina and Anaptychia ciliaris. He finds that there are two pro- 

 cesses of formation of the ascus : (1) by the " hook " formation, where the 

 median cell of the hypha becomes the ascus ; and (2) by the branching 

 of a hypha with synkarions, the terminal cells of the branches becoming 

 the asci. Galactinia succosa belongs to the latter type. 



After fusion of the two nuclei in the ascus of Galactinia, the first 

 nuclear division is " heterotypique," proved by the synapsis condition at 

 the prophase stage, and because of the behaviour of the chromosomes, 

 which divide during their ascent to the poles. The second division of 

 the nucleus is " homotypique ;" there are eight protochromosomes repre- 

 senting the half -chromosomes that were formed during the anaphase of 

 the preceding division. The third division is " typique " — there are only 

 four chromosomes formed in the early stage. He finds from his own 

 work and that of others, that this number, however, varies in different 

 species of Ascomycetes. He gives an account also of the formation of 

 centrosomes and spindle which have an intranuclear origin ; the polar 

 irradiations first described by Harper have an extranuclear origin. He 

 has also examined the secretions of latex in Galactinia ; certain hypha? 

 are laticiferous, as in the Basidomycetes. In the ascus there is also a 

 secretion of latex, which is not utilised by the nuclei, and is expelled 

 along with the spores. There are in addition minute oil drops in the 

 cytoplasm of the ascus, which gather round the nuclei and unite in the 

 spore into two large guttse. 



Bi-nucleate Cells in Ascomycetes.^— G. Maasee finda bi-nucleate 

 cells in the hypha and conidia of Hypomyces perniciomm, and that the 

 two nuclei present in the conidium fuse at an early stage of develop- 

 ment ; on germination, the germ-tube is uninucleate. He gives other 

 instances of binucleate cells in the Ascomycetes, and points out the 



* Ber. Deutsch. Bot. Gcsell., xxiii. (1905) pp. 197-202 (1 pi.). 

 t Ann. Mycol., iii. (1905) pp. 128-54 (If pis.). 

 X Ann. Bot.,xix. (1905) pp. 325-6. 



