54 BOTANICAL GAZETTE [july 



a nucleole appears clearly (fig. 24). The condition of the resting 

 spore at this stage corresponds to that found by Loewenthal (20) 

 in the sporange of Olpidium Dicksonii at the very beginning of 

 zoospore formation, when the presence of very numerous tiny 

 nuclei was noted. Before staining, the content of the resting 

 spore appears hyaline and refractive in section. Only the nuclei 

 stain deeply; about each nucleus is a clear region, the clear por- 

 tions being separated by lightly stained cytoplasm. 



It is only in the resting stage that the heavy-walled bodies 

 should be called spores. From the nature of their further develop- 

 ment they are clearly potential sporanges. The resting spores of 

 the Chytridiaceae have frequently been called sporanges. 



The development of the sporanges was first studied in Van 

 Tieghem cells, distilled water being the medium employed. The 

 spores undergo an immediate change when placed in water. The 

 granular appearance gives way to one in which the cell seems to 

 be filled wdth small globules of oil. This indicates the first changes 

 leading to the formation of zoospores. If the spores are crushed 

 at this stage, numerous globules of fat are freed which stain with 

 Sudan III or with osmic acid. As development continues, the 

 fat globules in the sporanges apparently become larger and less 

 numerous (fig. 14). This condition continues until the motile 

 zoospores are set free. 



In water the wall of the sporange also undergoes an almost 

 immediate change; a swelling of the wall on that side takes place, 

 presumably because of the entrance of water through the pores 

 in the depressed surface. Busgen (5) observed a somewhat simi- 

 lar swelling of the wall in the sporanges of Cladochytrium Butomi. 

 The sporanges become almost or quite spherical in outline. The 

 pores become cracks, and after a time the outer layer may rupture 

 as the inner content becomes more turgid (fig. 18). Various 

 appearances are brought about by the protrusion of the inner layer 

 of the wall and its contents. Sometimes the outer layer is thrown 

 off like a cap, as Busgen observed in his study of Cladochytrium. 

 In the majority of cases, however, the outer layer remains intact. 

 The whole process indicates a softening or gelatinization of the 

 wall as compared with its previous brittle condition. 



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