146 Vniversif)/ of California Puhlicationfi. [botany 



coalesceuce and interweavinj? of tlie outer mycelial branches, and 

 seems also to send out hranehes which radiate outwards to the 

 surface of the frond, forming a network between the algal cells. 

 At the upper surface of the perithecium, the mycelial filaments 

 which project close around the ostiole are not so coarse or so 

 deeply pigmented. This explains the pale color of the apex of 

 the perithecium. Just outside this circle of pale hypha? are the 

 coarse, deeply pigmented, and densely packed mycelial tips which 

 form a wider circle about the ostiole, and surround the isolated 

 groups of algal cells, or single cells scattered about irregularly, 

 and fill all the interspaces closely. From the ostiole itself, very 

 fine hyaline hairs project outwards. The developing perithecia 

 show, at first, a small lens-shaped collection of hypha? rich in 

 protoplasm in the center of the medulla. It soon becomes a 

 complex mass with three to five radiating centers from which 

 the protoplasmic ascogenous hyphse develop and are to be distin- 

 guished by their deep staining. The central portions and peri- 

 thecial walls take the stain less readily. Finally the central 

 tissues disappear and a layer of protoplasmic cells is formed on 

 the inside of the perithecial cavity, which later produces the asei. 

 By the expansion of the central cavity and the elongation and 

 increase of the medullary filaments, the outer lateral filaments 

 are pressed outwards, bulging out the cortical layer with its algal 

 cells, which are scattered and flattened in the process. During 

 this period the mycelial threads of the medulla are pressed 

 together, blended and interwoven, to form the pseudoparenchyma 

 of the perithecial walls. Just how the hyphal tissue in the center 

 is absorbed or spreads out to form the perithecial walls of delicate 

 cells surrounding the cavity was not distinctly seen, but probably 

 the fine hypha-like filaments radiating from the central placenta 

 interweave, coalesce, and in some way grow to the perithecial 

 wall as it is developing, and are spread out by their expansion 

 and growth to form this thin subhymenial layer. No doubt the 

 cavity within is greatly increased by the growth and expansion 

 of the developing asei which crowd from all sides toward the 

 center, filling it, forcing out the perithecial walls in every 

 direction, and thus flattening tangentially the cells of the inner 

 walls. Only the innermost layer contains granular protoplasm, 

 which is shown by eosin or hajmatoxylin staining. 



