Manchester Memoirs, Vol. Ivii. (191 3), No. 8. 9 



middle regions, and with the sterile cells pressing in 

 between their ends. The surrounding delicate thin- 

 walled tissue subsequently becomes collapsed and devoid 

 of contents, suggesting that it has functioned as nutriment 

 to the developing asci. 



Very young fruiting bodies are more or less globular 

 in form, the fertile elements occupying the centre. Later 

 growth is not equalh' centrifugal, the development being 

 greater toward the host periphery than toward the lumen, 

 (/v. //., Pigs. 16 — 18.) The result is a pear-shaped 

 structure, the tapering mass of tissue occupying the 

 position of the perithecial neck. When the ascocarp has 

 reached its mature size the wall layer becomes pigmented 

 and the cells slightly thickened at their angles. {PL /., 

 Fig. 15.) This does not extend over the distal surface 

 of the neck or ostiolar pad of tissue, but around it the 

 pigmentation and thickening are present in slightly in- 

 creased amount. The ostiole or canal is finally formed 

 by the degeneration of this pad of sterile thin-walled 

 tissue. 



VVoronin described the mature perithecium as follows : 

 " A fully grown normally developed perithecium attains a 

 size of about 05 mm., and has a rounded barrel or club- 

 shaped form. The entire perithecium is sunken in the 

 Lemanea thallus, only the ostiole appearing through the 

 cortical layer of the parenchymatous tissue of the alga. 

 The walls of the perithecium consist at the sides and the 

 apex of one or two la\ers of polygonal cells, with dark 

 brown coloration. On the base of the perithecium, 

 internal to the brown coat, is a delicate fine-celled paren- 

 chymatous tissue, whose elements are arranged in three 

 to five irregular layers. This is the so-called hymenial 

 la)'er, from which the asci, formed from the perithecium 

 nucleus, arise." 



