234 NATURAL HISTORY BULLETIN. 



the surface becomes broader until it ruptures the perithecium 

 and the hymenium is exposed in the form of a disc. At this 

 time branches are sent out from one of the cells of the ferti- 

 lized archicarp and are added to the subhymenial layer. These 

 branches are called the ascogenous hyphae. From the cells 

 of this tissue arise the spore bearing hyphae or asci, which 

 are thrust up between the paraph yses and continue to grow 

 until they reach the surface of the hymenium. 



The spores are formed endogenously by successive division 

 of the nucleus within the terminal cell of the ascus. The 

 number of spores in each ascus is generally two or some 

 multiple of two, increasing in the following ratio: — 2-4-8-16- 

 32-64-128. This complete series is represented among the 

 species described in this paper, with the exception of the first 

 and last. Hamaria tetraspora (Fckl.) Sacc, PI. XI Fig. 

 1, shows constantly four spores in each ascus. Any of the 

 common forms will show eight. Ryparobins sexdccimsporus 

 (Cr. ) Sacc, PI. XVIII Fig. 1, will show the next number in 

 the series which is sixteen. Thirty-two are found in each 

 ascus of Ryparobius pelletieri (Cr. ) Sacc, PI. XVII Fig. I 

 and sixty-four in Ryparobius crustaceus (Fckl.) Rehm., PI. 

 XVII Fig. 11. One other representative has been studied in 

 which there are more than sixty-four but the exact number 

 could not be determined definitely. In adddition to this series 

 some species which ordinarily have eight spores sometimes 

 contain only four or six. This has been found to occur in 

 plants of Ascobolus immcrsus Pers., PI. XVI Fig. 1, which 

 were grown in the laboratory. Several plants were examined 

 in each of which asci were found containing eight spores, 

 several in each plant also being found containing only four, 

 and in one or two cases, six. 



The arrangement of the spores in the ascus varies with 

 different species and genera and depends to some extent upon 

 their form. 



As to form, the sporidia may be spherical, elliptical, fusi- 

 form or spindle-shaped, or linear with many gradations 



