Morphologie, Befruchtung, Teratologie, Cytologie. 163 



These results maj^ be summarized thus. The conjugate condition 

 of the fertile cells of the aecidium is mainly the result of one of two 

 processes; either that of a nuclear migration from a vegetative cell 

 into a fertile cell {U. poae, Piic. poarinn, Phrag violacemn) or that of 

 fertile cells fusing in pairs {Phrag. speciosum^ Caeoma nitens^ U. Caladii, 

 M. Rostrupi). The gametophyte stage with Single nuclei may be 

 well-marked even in reduced forms 2l^ m Puc.malvaceanini jOr itmay 

 be inconspicuous as in U. Scillarinn and P«c. <7rt'o.r(7e , where it possibly 

 consists of little more than promycelium. The sporophyte stage with 

 its 3 kinds of spores is well-marked in forms with the entire life- 

 cycle, but in such forms as P. ntalvacearum it is represented only 

 by a few generations of cells. The author believes there is a reduction 

 of chromosomes at the first division of the promycelium. 



A. D. Cotton (Kew) 



Blaekman, H. Vernon & Helen C. I. Fräser On the Sexuality 

 and Development of the Ascocarp of Humaria granulata 

 Quel. (Proceedings Royal Society B. 77. p. 354. 3 plates. 1906). 



Humaria granulata, Quel. is a Discomycete the ascocarp of 

 which develops without fertilization by an antheridium, therefore the 

 cytological account of the progress recorded in this paper is of 

 special interest. 



The authors find there is a complete absence of an antheridium 

 but the female nuclei fuse in pairs in the ascogonium, which must 

 be regarded as a reduced type of fertilization. The details of the 

 process are as follows. The beginning of the archicarp consists of a 

 branch with a variable number of somewhat short cells. The apical 

 cell of this row is the ascogonium which soon increases in size and 

 becomes spherical. Before the ascogonium has attained its füll size 

 a number of branches begin to grow out from the cells of the stalk 

 immediately below; these are vegetative hyphae which grow up and 

 completeh' invest the ascogonium and Upper cells of the stalk. No 

 antheridium is developed. The ascogonium shows well defined nuclei 

 which later increase enormously in number. The increase is due to 

 nuclear division, as there are no nuclear migrations into the asco- 

 gonium. There appears to be no definite stage of fusion for all the 

 nuclei, corresponding to that of Pyronema , but a gradual fusion in 

 pairs takes place in the ascogonium as development of the ascogenous 

 hyphae proceeds. The latter are thin-walled and grow out through the 

 mass of investing hyphae. Nuclei and cytoplasm pass into them from 

 the ascogonium. The later stages in the development do not require 

 comment. The formation of the asci and spores resembles that descri- 

 bed by Harper for other Discofnycetes. 



A general discussion closes the paper, in which the nature of 

 sexual fusions, the fusion in the ascus, and other points are dealt with. 

 The authors insist that the fusion in pairs of the female nuclei must 

 be considered as a reduced sexual process and cannot be classed with 

 asexual fusions as advocated b}'- Davis. It is suggested that the 

 term archicarp should be used for the whole fertile branch (apart 

 from the antheridium) and that the term ascogonium should be con- 

 fined to that part of the archicarp the contents of which take part 

 in the formation of ascogonous hyphae, i. e. the reproductive cell or 

 cells which contain the female nuclei. A. D. Cotton (Kew) 



