LABOULBENIALES 371 



the perithecium. It lies directly beside p. The cell i, however, divides 

 in the plane of the picture into two daughter cells, so that one lies in front 

 and one behind, and hence cannot be shown in the picture. Cells ii 

 and z begin to grow upwards and surround cell d, the primordial cell 

 of the archicarp. 



The cell z subsequently divides into o' and n (Fig. 248, 13) ; one of the 

 cells, ii divides similarly into cells o and n, while the other, here not 

 indicated, divides into a lower and two upper cells. Those three cells, 

 o, o' and o" , not indicated in our figure, which arose from the division 

 of the second cell ii, form the true basal cells of the perithecium. They 

 remain undivided while the four cells n in time will develop to the four 

 cell rows of the outer perithecial walls. 



Meanwhile cell d has divided into two daughter cells / and g (Fig. 

 248, 13). The former is surrounded by the four cells n and the three 

 cells o, the latter projects into the open. 



The cell e cuts off the small tip cell e' (Fig. 248, 14) which develops 

 terminally to a trichogyne. In sexually mature individuals, the archicarp 

 consists of three distinct parts which, as far as known, are present in all 

 Laboulbeniales ; a trichogyne which in the present example is unicellular, 

 the cell e" which is called the trichoporic cell and cell / which is called 

 the carpogenic cell, since it forms the true fertile cell. 



During this time numerous spermatia have clung to the receptive 

 prominences 1 of the trichogyne, and apparently, as in Collema crispum, 

 there occurs a sexual act and nuclear migration ; in any case the trichogyne 

 collapses shortly, while the carpogenic cell divides into three daughter 

 cells (Fig. 248, 16), into the superior supporting cell ot, the inferior sup- 

 porting cell ut and the middle ascogonium /'. This divides again into 

 two daughter cells, a lower sut and an upper f". The lower remains 

 unaltered and forms the secondary supporting cell. The cell /" divides 

 by longitudinal walls into four daughter cells, of which, in the figure, 

 only the front two are indicated (Fig. 248, 17) ; these are the four ascogenic 

 cells which successively produce two rows of asci as in any other 

 Laboulbeniales. 



Meanwhile the perithecial wall has continued to develop. The three 

 basal cells o, o' and o" ', have developed in the interior the four 

 original primary cells n of the outer perithecial walls to four new 

 secondary wall cells n" , which alternate with the four primary. The 

 outer wall cells n divide each into an upper daughter cell w and a lower 

 daughter cell n' ; then the inner wall cells n" each divide into a lower 

 daughter cell pc and an upper daughter cell nc (Fig. 248, 16). The four 



1 Doctor Thaxter informs me that the structures represented on the trichogynes 

 in these figures are not adherent spermatia as formerly supposed, but are receptive 

 prominences of the trichogyne itself, similar to those figured in Acompsomyces 

 (Thaxter, 1908, pi. 42, figs. 8 and 12). 



