12 REPORT OF THE COMMISSIONER OF AGRICULTURE 



drawings, with.tlie view of sbowing the character of cryptogamic micro- 

 scopic fungi, edible and poisonous mushrooms, textile fibers, &c., for the 

 Centennial Exhibition, amounting in all to about six hundred specimens, 

 and now forming part of the Government exhibit, the largest proportion 

 representing the leading types of the genera of microscopic fungi ; the 

 results of original investigations upon chemical tests for flax, cotton, 

 ramie, silk, wool, hair, and cellulose ; and still another series, illustrating 

 the principal vegetable starches, to the number of about one hundred 

 varieties. These drawings present highly-magnified views of all these mi- 

 croscopic objects, including those most important in economic mycology, 

 especially the fungi commonly known as molds, so destructive to vege- 

 tation. The edible and poisonous mushrooms are distinguished in one 

 class of these drawings. The molds of cheese, bread, and jellies are 

 illustrated, and their habits of growth shown, a knowledge of which 

 may often be useful for practical purposes. ^ 



Another series of drawings illustrates the action of pear-tree blight, 

 showing the effects of the chemical changes which take place in the inte- 

 rior structure of the tree under the attacks of the fungus to which this 

 disease is due. Black-knot is illustrated in a similar manner, some of 

 the drawings exhibiting it as it appears to the naked eye, while others 

 show in detail its distorted, woody structure. The fungus which pro- 

 duces it is also shown at various stages of its growth. 



The fungus Peronospora infestansy which causes potato-rot, is illus- 

 trated in the various stages of its growth. There is also a series of 

 drawings of its resting spores, recently discovered by Mr. Worthington 

 Smith, of London, so named from the fact that they remain for months 

 in a stationary condition, or, in other words, rest for a long time with- 

 out germinating. 



The importance of the mushroom as an article of diet has never been 

 properly understood in the United States, nor is it generally known how 

 abundant our supply of edible mushrooms is. Many of those popularly 

 supposed to be poisonous are not merely innocuous but highly nutritious, 

 containing as they do many of the elements of animal food. In France, 

 Germany, and Italy, the mushroom forms so important a part of the 

 food of the people, that one distinguished writer has spoken of it as 

 " the manna of the poor." In Transylvania, the oyster-mushroom is so 

 abundant and is so largely used, that tons of it may often be seen in the 

 markets ; and in some parts of Germany the Morel mushroom is so 

 popular, that the people, finding it to grow best on a soil treated with 

 wood-ashes, were accustomed to burn down portions of the forest in or- 

 der to secure favorable spots for its cultivation ; a practice which the 

 government ultimately found it necessary to interdict. 



Particular pains have been taken to represent the types of the edible 

 mushrooms of this country as fully as possible, a number of collectors 

 having been employed for the purpose in various parts of the United 

 States. Among these may be mentioned Professor Peck, botanist of 



