218 TRANSACTIONS OF THE ILLINOIS 



Zoospores. The spores of all other fungi, upon germination, throw out one 

 or more threads, which directly or indirectly reproduce the plant, but, 

 though the same thing often occurs here, the more common thing is the 

 division of the spore into five or six portions, which become free by the 

 rupture of the spore coat. On each part two very fine hair-like append- 

 ages are produced, which become locomotive organs, propelling the little 

 body for some minutes or hours through the drop of water in which they 

 originate, with astonishing rapidity, as seen under the microscope. Hav- 

 ing had their "run," they settle down and germinate like an ordinary 

 spore. . The term zoospore has been given on account of these motions, 

 which were supposed, at one time, to be peculiar to animals. Besides 

 multiplying greatly the germinating bodies, the zoospores doubtless aid 

 greatly in the dissemination of the species. Another and more proper 

 form of fruit is produced, not, however, so strictly confined to this group, 

 the so-called Oospore. This arises from a process of fertilization, anala- 

 gous to that brought about by pollen in flowering plants. The oospore 

 is the winter spore, the others probably perishing during that season. In 

 the spring it, too, splits up into zoospores, which appear in every way 

 similar to those spoken of above. Much interest has lately been taken in 

 the finding of the oospores in the potato fungus, by G. Worthington 

 Smith, of England. Its existence had not before been certainly known 

 as such, though really it had been observed several times and named as 

 belonging to another species. But the great loss caused by this fungus, 

 and the hopes of finding some remedy, set many sharp eyes to investigat- 

 ing its development. We wonder now that Mr. Smith's discovery was 

 not made long before. The fact is now, however, known that this para- 

 site, causing the rot of potatoes, is preserved during winter in the old 

 stems or vines and in diseased tubes. Mr. Smith has followed up his dis- 

 covery by making some compound of sulphur, potash, etc., which is to 

 be tried on a large scale in England, by application to the seed tubers, 

 the vines of course being carefullv burned. In the moist climate of 

 England this disease is much worse than with us, which is bad enough. 

 The remedy, if indeed it proves such, will be a blessing little short of 

 that of the potato itself. As far as observed by myself, the tomato was 

 more injured last season than the potato ; the leaves were sometimes 

 white with the fungus and the fruit decayed badly. 



The Lettuce mould was quite fully described in the report of the 

 Society last year, and is therefore omitted here, except to say that its 

 ravages were not so bad as the year previous. 



Feronospora viticola was very destructive on grapes during the two 

 last summers. The smooth-leafed varieties, especially, were greatly in- 

 jured. The leaves and young stems first exhibited a whitened, mildewed 

 appearance ; these died and were replaced by others, which were killed 

 before the leaves attained more than half their normal size. The fruit 

 did not seem to be directly attacked, in most cases, but perished with the 

 repeated destruction of the leaves. The growth gradually became weaker, 

 the struggling shoots smaller and more starved, and in many cases the first 



