356 Mr. Blackmail and Miss Fraser. Sexuality and [Oct, 31, 



of the stalk and completely invested the apical cell. The large cell he 

 considered to be of the nature of an egg, while one of the branches growing 

 up from below he thought was probably of the nature of an antheridium ; he 

 was unable, however, to follow any further details of development. 



Actual Observations. — As Woronin observed, the first beginning of the 

 archicarp consists of a branch with a variable number of somewhat short 

 cells (figs. 2a, 2b, 3). The apical cell of this row is the ascogonium* which 

 soon increases in size and becomes spherical, and exhibits beautiful vacuolate 

 structure (figs. 2a, 2b). The lower cells also increase in size and both they 

 and the ascogonium become closely filled with food-material, so that the 

 whole archicarp has a dense and opaque appearance (figs. 4, 5). Before the 

 ascogonium has attained its full size a number of narrow branches begin to 

 grow out from the cells of the stalk immediately below (fig. 4). These are 

 the first beginnings of the investing hyphte which soon grow up and com- 

 pletely cover in with layers of plectenchyma the ascogonium and upper few 

 cells of the stalk (figs. 5, 9). In cleared preparations, however, the cells of 

 the ascogonium and of the stalk, owing to their greater density, can, for a 

 time, be distinctly seen through the investing sheath (fig. 5). 



The number of cells in the stalk is variable ; there may be only a few, as 

 is apparently the case in fig. 3, but usually a large number are to be 

 observed, as in fig. 5. From one of the cells about the middle of the stalk a 

 small side branch was sometimes seen which grew down into the substratum 

 and apparently aided the stalk in absorbing nourishment. 



None of the hyphse which grow up from the stalk act in the way Woronin 

 suggested ; they are all mere vegetative investing hypha;, no antheridium 

 being developed. 



The ascogonium shows a vacuolate protoplasm with a number of nuclei 

 which are better defined than those of the vegetative cells ; with the growth 

 of this organ these nuclei become much more distinct, exhibiting a nuclear 

 membrane and a single deeply-staining nucleolus (figs. 6, 7), but no 

 chromatin is to be observed in the nuclear cavity. As development proceeds 

 the nuclei increase only slightly in size but enormously in number ; and the 

 small vacuoles are replaced by one or more large ones (figs. 8, 10). At about 

 the stage when the vegetative hyphae completely surround the ascogonium, 

 the wall of the lattei becomes thickened and shows a distinct differentiation 

 into two layers, the outer, thin and deeply staining, the inner, thicker and 

 lightly staining (figs. 10, 11). 



The wall between the ascogonium and the uppermost stalk cell exhibits at 

 a young stage the usual apposed groups of granules, but at a later stage the 

 * For a discussion of this use of the terms archicarp and ascogonium, vide infra. 



