236 



BOTANY. 



hyphge, which produce few or many separable reproductive 

 cells the spores (Fig. 158). The method of formation of 

 the spores in Mucor Mucedo is as follows : the vertical hy- 

 phge, which are filled with protoplasm, become enlarged at 



the top, and in each 

 a transverse partition 

 forms (A, a, Fig. 159), 

 the portion above the 

 partition (b, Fig. 159) 

 becomes larger, and, 

 at the same time, the 

 transverse partition 

 arches up (B, a, Fig. 

 159), finally appearing 

 like an extension of 

 the hypha, then called 



Fig. 158.-Diagram showing the mode of growth ^ ne Columella (0, d, 

 of Mucor Mucedo. m, the mycelium : s, single 



sporangium, borne on an aerial erect hypha. After 



3 rantl. 



Fig. 159). The pro- 

 toplasm in the en- 

 larged terminal cell (b) divides into a large number of 

 minute masses, each of which surrounds itself with a cell- 

 wall ; these little cells are the spores, and the large mother- 

 cell is now a sporangium. 



In the other Moulds the process is essentially like that 

 in Mucor Mucedo. In 

 many cases there are sev- 

 eral sporangia formed at 

 the top of the vertical 

 hyphse ; in such cases the 

 latter are branched before 

 the formation of sporan- 

 gia. Another variation 

 from the method as de- 

 scribed above is that 



in 



Fig. 159. Diagrams showing mode of 

 growth of the sporangium of Mucor Mucedo. 

 A, very young stage ; B, somewhat later ; C, 

 , sporangium with ripe spores, a in all the fig- 



SOme Species DUt One Spore ures represents the partition wall between the 

 j 1 last cell of the filament and the sporangium b. 



is formed in each sporan- 

 gium ; the hyphae then appear to bear naked spores. 



317. The spores are set free in different ways; in some 

 cases the wall of the sporangium is entirely absorbed by the 

 time the spores are mature ; in other cases only portions of 



