14 



MYCOLOGY 



rather uniformly through the spore plasm and are of unequal size. 

 Vacuoles are formed in a still further condensation of the sporangial 

 protoplasm and each of these apparent vacuoles is pierced by a capilli- 

 tial thread which runs through its central axis. Droplets of water are 

 formed along the capilUtial thread as a still further evidence of water 

 extrusion. Cleavage planes now appear at the periphery of the mass 

 of sporangial protoplasm and progress inwardly toward the center. 

 The process of cleavage parallels the extrusion of water and the for- 

 mation of the blocks of protoplasm by these cleavage lines is assisted 



Fig. 2. — A,B, Comalricha nigra. A, Sporangium, natural size; B, capillitium, 

 20/1; C, £, Stemonitis fusca; C, sporangium, natural size; D and E, capillitia, 5/1, 

 20/1; F, H, JLnerlhema papillatum, F, unripe; G, mature sporangium, lo/i; H, capil- 

 litium, 20/1. (C D, after nature. A, F, G, H, after Roslafinski; B, E, after de Bary 

 in Die natiirlichen PJlanzenfamilien I. i, p. 26.) 



by the presence of the vacuoles. The splitting up of the irregular blocks 

 of protoplasm, which have the nuclei irregularly distributed through 

 them, proceeds until the protoplasmic blocks arebinucleated, and before 

 this the nuclei are seen in various stages of division which proceeds 

 irregularly in Didymium, while in Fuligo the division of the nuclei is 

 simultaneous in a particular spore sack. The plasma membranes of 

 the capillitial openings are the source of cleavage furrows to even a 

 greater degree than the original surface plasma membrane of the spore 

 sack as a whole. In Fuligo in the final stages of spore formation the 

 spore plasm is condensed about the nuclei, but in Didymium, the ultimate 



