242 DISEASES OF FIELD & GARDEN CROPS. [OH. 



never seen the Peronospora in anatomical connection with 

 the Protomyces. 



An illustration of Protomyces macrosporus, Ung., is given 

 in Fig. 113, enlarged 400 diameters. These bodies, which 

 'are true oospores or resting-spores, have two or three mem- 

 branes, and when small in size, as at C, are hardly to be 

 distinguished from the resting-spores of Peronospora nivea, 

 Ung. When, however, they are of large size (and they 

 vary greatly), and furnished with a dissepiment across 

 the inner or endospore, as at B, they are unlike the usual 

 resting-spores belonging to Peronospora. These bodies 



A B 



FIG. 113. 

 Protomyces viacrosporus, Ung. Enlarged 400 diameters. 



occur in the intercellular spaces within the leaves and 

 stems of umbelliferous plants, often in large companies. 

 They not only cause decomposed spots to appear, but they 

 distort and distend the affected parts in a remarkable 

 manner ; so much is this the case that the presence of the 

 fungus within is easily detected by the knotty swellings 

 they set up. As the spores reach maturity they cause the 

 tissues of the leaf to rot, and by this means they reach the 

 ground by falling from the decayed places. They doubt- 

 lessly rest on and in the ground in a hybernating state 

 till the following spring or summer. Mr. Berkeley says 

 the Protomyces is probably one form of fructification of the 

 Peronospora, In. this he agrees with Caspary ; but De Bary 



