i6 



RESEARCHES ON FUNGI 



Fig. 8. — Pilobolus crystallinus. Cytology of 

 the sporangium (continued) and of ger- 

 minating spores. A, a multinuclear 

 cell (embryonic cell) developed from a 

 protospore, about to undergo constric- 

 tion ; nuclei arranging themselves in 

 two groups and a central zone be- 

 coming hyaline. B, a similar cell, 

 slightly older. C, a still older cell 

 undergoing constriction into two 

 halves. D, outline drawing of part of a 

 median section through a sporangium 

 with binucleated spores (formed by 

 growth and constriction of proto- 

 spores) : a, wall of columella; 6, proto- 

 plasm of columella containing many 

 nuclei ; c, sporangial wall ; d, gela- 

 tinous collar with extension upwards 

 on the columella ; e, binucleated spor- 

 angiospores; and/, intersporal homo- 

 geneous slime. E, living spore about 

 to germinate in a nutrient medium. 

 F, spore swollen and germinating in 

 a nutrient medium. G, germinated 

 spore with its germ-tvibe, with 

 numerous nuclei. Magiiification : 

 A-C, E-G, 824; D, not stated. Copied 

 by the author from R. Harper's Cell- 

 Division in Sporangia and Asci 

 (Annals of Botany, Vol. XIII, 1899, 

 Plate XXV). 



furrows then appear around 

 the base of the sporangium (/) 

 cutting the surface of the 

 protoplasm into irregular poly- 

 gonal areas. The rounded 

 vacuoles in the interior of the 

 protoplasm become angular (g), 

 and their edges cut through the 

 protoplasm to meet similar 

 cleavage furrows from adjacent 

 vacuoles. The surface furrows 

 grow deeper and meet and be- 

 come continuous with the edges 

 of the vacuoles. The spore- 

 plasma thus becomes roughly 

 marked into blocks of irregular 

 size containing a variable num- 

 ber of nuclei. Further furrowing 

 cuts these first-formed blocks 

 into oblong rounded sausage- 

 shaped masses generally con- 

 taining two to four nuclei in a row 

 (Fig. 7,F). These oblong bodies 

 are now divided transversely to 

 form rounded or spherical masses 

 each with one or a few nuclfei 

 (Fig. 7, G). The protospores so 

 formed now begin to grow, 

 and their nuclei divide rapidly 

 (Fig. 7, H) so that the masses 

 once more become multinucle- 

 ated (Fig. 8, A). Then each cell 

 divides by constriction, the nuclei 

 being separated into two groups 

 in the halves so formed (Fig. 8, 

 A-C). The nuclei may then 

 divide further, their division 

 being followed by further cell- 



