134 Extracts from the Journals. [Jan., 



white and black spots, as a number of minute projections, or frosty 

 incrustations, or a brownish powder, spreading more or less rapid- 

 ly, till the plant is destroyed. Mildew is fungi of different kinds, 

 and these are divided into three classes: 1st, those which grow or 

 lie on the surface of leaves; 2d, those which are formed in the 

 interior of the stem or leaf, and produce when ripe; and 3d, those 

 which only attack the roots. All these seldom appear but in au- 

 tumn. 



The first of these fungi injure the plant by preventing its respi- 

 ration. One of the most common of the fungi, which attack the 

 common cabbage, is the cyliiidrosporium concentricuin, and they 

 have the appearance of small white patches or specks of frosty 

 incrustation. The mildew w^hich attacks rose-bushes, and many 

 other flowering shrubs, is a kind of uredo, so called, from ura, to 

 burn or scorch: for it gives to the plant attacked the appearance 

 of being scorched. The fungus called acrosporium, monilioides, 

 resembles, when magnified, a string of beads, and consists of a 

 number of globules which, when ripe, fall, take root, and form 

 fresh strings, or necklaces. Sometimes tufts of these appear, 

 fixed to stalks, and are then called aspergillus, from their fancied 

 resemblance to the brushes used for sprinkling holy water. The 

 superficial mildew which infects the onion, and is fatal to that 

 plant, is called hotrytis, or bunch of grapes. The bean and pea 

 have a superficial mildew (uredo f aha) which spreads along their 

 leaves like white roots curiously interlaced. 



The second class of fungi which spring from the interior of the 

 leaves and stems, are the most fatal. They appear in a sort of 

 bag or case, supposed to be formed of the cuticle of the affected 

 leaf These attack the oak, pine, and other forest trees; the ge- 

 nus is the cecidium. The cecidium pine, found on pine trees has, 

 when magnified, the appearance of a number of nine-pins. When 

 ripe, it emits a bright orange-colored powder. A mildew of this 

 kind attacks barley, and is very injurious. It is vulgarly called 

 pepper brand. The urego segetum, or smut, is destructive not 

 only to barley, but to wheat and oats. It destroys the grain, 

 which is converted into a kind of jelly, and attacks the leaves and 

 stems. The puccinia granmvis, which attacks corn, is formed in 

 the interior of the stock, and, when ripe, burst forth into clusters, 

 like bunches of grapes, of a dark brown color. The ergot on rye 

 is a well known and destructive species of mildew. It grows out 

 of a spike of grain, like a prolonged kernel; is long, horney and 

 cartilaginous. It originates in the centre of the stem. It affects 

 maize, and various species of grass. 



The principal fungi of the third class are two, which attack the 

 roots of plants, and both resemble tiuffles. One of these {rhizoc- 

 tonia crocorum) attacks crocuses. It is called, by the French, 



