324 SUMMARY OF CURRENT RESEARCHES RELATING TO 



BOTANY. 



GENERAL, 



Including the Anatomy and Physiology of Seed Plants. 



Cytology, 

 including: Cell Contents. 



Micro-chemistry.* — 0. Richter gives a very useful account of the 

 advances in botanical micro -chemistry since the appearance of Zimmer- 

 mann's 'Botanischer Mikrotechnik,' in 1892. There is also a useful list 

 of new vegetable substances which have been described of late years, 

 with the name of their discoverer, and a description of their nature. 



Protoplasmic Continuity.! — T. Wulff has studied protoplasmic 

 continuity in Monocotyledons, and has demonstrated the existence of 

 " plasmodesmen " between the mesophyll cells and the mesophyll and 

 epidermal cells of the leaf of various cereals ; and between the endo- 

 sperm cells and the cells of the aleurone layer in the seed of oats. 



Sexuality of Ascomycetes.f — Although the presence of a normal 

 sexual fusion of nuclei — in addition to the ascus fusion — is now 

 indisputably proved for a number of Ascomycetes, yet normal sexuality 

 is clearly not present in all cases. A number of forms have been known 

 for some time in which there is no antheridium, but the development is 

 otherwise normal. V. H. Blackman and H. C. Fraser have for the 

 first time investigated one of these forms cytologically. In Humaria 

 granulata, a coprophilous member of the Discomycetes, the ascogonium, 

 which is a multi-nucleate " ccenogamete," like that of Pyronema, is 

 borne on the end of a short branch. The ascogonium develops normal 

 ascogenous hyphge, but there is no antheridium, and, therefore, no cell 

 fusion. The fusion between male and female nuclei is, however, re- 

 placed by a fusion in pairs of the female nuclei of the ascogonium. This 

 type of fusion must obviously be considered as a " reduced fertilisation " 

 comparable to that found in the aecidium of the Uredineae ; the male 

 cells in both cases having either disappeared or become abortive. The 

 authors suggest that this type of fertilisation will probably be found to 

 be more common in the Ascomycetes than the normal sexual fusion. 



Sexuality of Uredineae .§ — V. H. Blackman and H. C. Fraser have 

 continued the observations of the first named author. They show that 

 nuclear migrations are to be found in connection with the basal cells 

 of the aecidium in Uromyces Poce and Puccinia Poarum ; while in 

 Melampsora\ Rostrupi the fertile (female) cells of the aecidium fuse in 



* Zeitschr. Wiss. Mikrosk. xxii. (1905) pp. 194-261. 



t Arkiv Bot., v. (1905) No. 2, pp. 1-20 (1 pi.). 



\ Proc. Roy. Soc, Series B, lxxvii. (1906) pp. 354-68, pis. 13-15. 



§ Ann. of Bot., xx. (1906) pp. 35-48, pis. 3, 4. 



