338 Bulletin 73. 



below. The lower ends of the cells of the hymenium begin 

 usually to intrude themselves between the cells of the epidermis 

 at quite an early stage of development. Fig. 47 shows this rela- 

 tion of the cells of the hymenium to the epidermal cells. This 

 results from a peculiarity of the development of the ascogenous 

 cells from the first mycelium which spreads beneath the cuticle. 

 The growth from these cells proceeds inward, that is, toward the 

 epidermis, as well as outward in the direction of the formation of. 

 the ascus. This is quite markedly the case in all the long stalked 

 species of Exoascus which I have examined, even of E. pruni, 

 E. communis, E. niirabilis, and others. It is however much more 

 marked in this species than in those just quoted, especially the 

 long inward growth of the stalk cells. After many of the asci 

 are quite well developed and are somewhat crowded, the hymen- 

 ium continues to increase in a peculiar manner in all of these 

 species but more so in some than in others. An ascogenous cell 

 develops somewhat below the middle a slender branch which 

 grows inward toward the epidermis. After having grown down- 

 ward for some distance, sometimes having reached a length of 

 15-20, the outer end begins to grow outward to form the ascus. 

 A series of these with a young ascus is shown in fig. 49. In this 

 way the lower ends of the stalk cells will frequently be at a very 

 irregular line, some of them not intruding between the cells of 

 the epidermis while others are crowded far down between them. 

 Exoascus rostrupianus probably develops the later hymenium in 

 this way to judge from Sadebeck's description, and also from the 

 fact that it is a long stalked species. But according to Sadebeck* 

 the stalks do not intrude themselves in the least between the epi- 

 dermal cells. The spores are also quite different, being quite 

 constantly elliptical, and the conidial formation from budding of 

 the spores in the ascus being very rare. The spores in E. longipes 

 are round or oval, measuring 3-4 in diameter. 



When the asci are developing from these later hymenial cells it 

 frequently happens that the septum separating the stalk cell from 

 the ascus is formed below the connection of the fruit body with 

 its neighbor from which it had its origin. 



* Die parasitischen Exoascecn, Ab. a. d. Jahrb. d. Hamb. Wiss. Anst. X, 

 2P-, 29, 1893. 



