188 



CRYPTOGAMS 



the chief danger which besets all very small organisms 

 exposed in the air, namely, drying. Where the Fungus 

 spreads away from the bread along the bottom of the 

 dish, it is seen that the sporangial stalks arise in groups 

 at points where the hyphse touch the dish, at which 

 points also rootlike organs appear (whence the name 

 Rhizopus, root footed). The whole has very much the 

 habit of a Strawberry plant propagating by runners 

 (Fig. 303). 



A B 



306. Germination of 307. Conjugation of Rhizopus : A, B, C, D, suc- 



the spore. cessive stages in the production of the 



zygospore. 



447. Under certain conditions short lateral branches 

 spring out near one another from neighboring hyphse and 

 grow until their tips are in contact (Fig. 307). The 

 end parts of the branches become cut off by septa. They 

 are the gametes, which fuse after the walls have been 

 absorbed at the point of contact. The result is the 

 formation of a thick-walled resting spore, or zygospore 

 (Fig. 307, z). 



Water Molds (Saprolegniaceae) 



448. The best way to secure material for the study of 

 these plants is to bring in a large handful of decaying 

 leaves from some pond hole or bog where water stands, 

 throw them into a jar of water, and after them throw in 

 either dead insects or succulent shoots of seedlings killed 

 by heat. Upon these food materials the spores of the 

 Water Molds from the dead leaves will fasten and ger- 



