CONJUGA TING FUNGI— PH YCOM YCE TES 



233 



of their favourite host. Thus, by asexual reproduction during 

 the summer, and by hybernation of the oospores through the 

 winter, provision is made for the continuance of the species. 

 Incidentally, it may be observed that in one genus, that of 

 Cystopus, the habit of the parasites is but little like that of the 

 residue of the Peronosporaceae : the conidiophores are extremely 

 short and simple, and the con- 

 idia are produced in chains ; 

 but the sexual reproduction by 

 oospores is virtually the same, 

 and this is almost the only 

 link which unites them. It is 

 worthy of remembrance here 

 that there is manifest in this 

 group a gradual loss of sex- 

 uality, although external feat- 

 ures remain much the same. 



The Saprolegniaceae, from 

 their aquatic habit, would at 

 first seem to have an afiinity 

 with Algae, rather than with 

 Fungi, but this is rather 

 analogy than affinity. The 

 hyphae, in most cases, are 

 modified at their extremity, 

 and become zoosporangia, 

 which are elongated cells 

 separated from the rest of the 

 hypha by a septum (Fig. 108). 

 After the zoogonidia have 

 escaped through an opening at 

 the apex, the hypha, or stem, 

 continues to grow up through 

 the empty sporangium, and 



forms a second sporangium, and this, in like manner, when the 

 zoogonidia are discharged, may enclose a third, so that upon 

 old threads it is not unusual to see the remains of two or three 

 empty sporangia, the one within the other. The zoogonidia 

 are produced in great numbers, in each zoosporangium, having 



-Sporangia and zoospores of 

 Saprolegnia. 



