THE WATER MOLDS 



243 



fishes in hatcheries and may be very destructive. The coenocytic 

 hyphae live in the tissues of the animal, and filaments grow out 

 from them freely into the water, 

 where they develop the repro- 

 ductive organs. 



Zoospores are formed numer- 

 ously in terminal club-shaped 

 sporangia and are discharged 

 into the water (Fig. 214, C, D). 

 They are two-ciliate and consti- 

 tute the method of rapid mul- 

 tiplication, swimming about in 

 the water, seeking a favorable 

 substratum on which to settle 

 down. 



The sexual organs are male 

 and female. Globular oogonia 

 are formed at the ends of cer- 

 tain hyphae, and each develops 

 a number of eggs (Fig. 214, F). 

 The male organs are delicate 

 antheridial filaments which 

 arise below the oogonia or from 

 neighboring hyphee. These ap- 

 ply themselves to the oogonia 

 and send delicate tubes (con- 

 jugation tubes) into the interior, 

 which in some forms are said 

 to unite with the eggs. How- 

 ever, it is known that the antheridial filaments in many of 

 the water molds perform no function, and indeed are not even 

 present in some types. In such cases the eggs mature into 

 oospores without fertilization. The water molds furnish, then, 

 excellent illustrations of the degeneration of a sexual process, a 

 phenomenon found in other groups of fungi 



FIG. 213. Formation of zygospores 

 in a mold (Mucor Mucedo) 



A, two hyphae in contact, end to end; 

 B, the terminal gametes; C, later 

 stage, the gametes fusing; D, a ripe 

 zygospore ; E, germination of a zygo- 

 spore, the filament forming a spo- 

 rangium at once in this case. After 

 Brefeld 



