HOW FUNGI LIVE IN WINTER. 



615 



concentrated and protected, thus enabling the fungus to survive an 

 exposure that might otherwise prove fatal. It should also be kept in 

 mind that the substance of the leaf in which these spores are imbedded 

 aids in shielding them from harm. If the vineyardist could destroy 

 all these sexual spores at the end of the growing season, he would 

 have little further trouble from the destructive mildew. 



The members of the Cruciferce, or cabbage family of plants, are 

 quite generally attacked by white molds — so called because they 

 cover the affected parts with a coating of almost pure white. A 

 much magnified (four hundred times) view of the non-sexual spores is 

 seen in Fig. 4. The white spores are produced in rows, forming be- 



FiG. 4.— Summer Spoeks op White Molds. 



low and falling away from the top, in the simplest possible manner. 

 The contents of the spores divide in germination as in the grape- 

 mildew above described. A ruptured spore is shown one thousand 

 times magnified, in the lower right-hand corner of the figure, while the 

 ciliated protoplasmic bodies (zoospores) are seen above. These white 

 molds are provided with sexual winter spores very similar to those 

 described for the grape-mildew ; in fact, the two groups are closely 

 related, and belong to the same family of fungi. Fig. 5 shows the 

 mature sexual spores of Cystojms cancUdus, magnified four hundred 

 diameters, one of which has its hard shell ruptured and its contents of 

 zoospores escaping. It requires weeks and even months for the de- 

 velopment of these sexual spores, and frequently a long time may 

 elapse before germination takes place. On this account they have 

 received the very appropriate name of resting-spores. They remain 

 within the tissue of the plant, and are frequently liberated only by its 

 decay. The life of the white molds passes over from one season to an- 

 other in these rough, thick-coated spheres of protoplasm, the formation 

 of which approaches in complexity that of the seeds of higher plants. 



