REPORTS OF AUXILIARY SOCIETIES. 2G3 



classification. They ditfer from nearly all other jjlants in having no chloro- 

 phyll, the substance that gives to leaves their green color and enables plants 

 that contain it to elaborate their own food from the mineral constituents of 

 the atmos])here and soil. The fungi, being destitute of chlorophyll, arc under 

 the necessity of obtaining this food already prepared for them wholly or in part 

 by other plants, and accordingly we find them either growing upon living plants 

 or animals as parasites, or they fasten upon and gather nutriment from dead 

 animal or vegetable material. The peculiar structure of the fungi adapts them 

 for their parasitic habits. They are made up of long, irregular, often inter- 

 woven threads or tubes that work their way through the tissues of the plant or 

 animal substance upon which they live, and in many cases are provided with 

 curious suckers which aid still further in abstracting the juices of their host, 

 as the oi'ganism upon which they feed is called. These tubes are thick-walled, 

 firm, and tough, and as a rule are much less easily injured than the cells of 

 the plant in which they are growing, a fact that renders it all the more difficult 

 to destroy the fungus without seriously injuring its host. 



After growing for a longer or shorter period in this way, at the expense of the 

 plant or other organic material upon which it has fastened, the fungus produces 

 an abundant crop of spores (corresponding to the seeds of flowering plants), 

 and in this way secures its own multiplication and the continuance of the mis- 

 chief of which it is the cause. To render the perpetuity of their kind doubly 

 sure, nearly all fungi produce at least two kinds of spores, and some of them as 

 many as three or four, of different forms and sizes. Some of these are small and 

 light, and are borne away by the wind to other individuals of the same host, 

 upon which they grow immediately; others are large and hard, covered with a 

 firm wall lor resisting all extremes of temperature, and in this way their growth, 

 after the vicissitudes of winter, under the returning warmth of spring, is pro- 

 vided for. Then, as if to successfully elude the search of man for his minute 

 but effective enemy, some of these germinate and grow on plants totally differ- 

 ent from the one on which the fungus began its development, and assume a 

 form that would not be suspected of having the remotest relationshij? with its 

 earlier stages. Living in this way for a time upon its new host, it at last 

 returns to attack in its original form the plant with Avhich it started. Add to 

 all this the immense number of species, some thousands of which have been 

 enumerated as occurring in the United States, and no surprise need be felt that 

 the fungoid diseases of trees and other plants are not all known and the means 

 of their extermination pointed out; indeed, it is a matter of congratulation that 

 so considerable an amount of information concerning them has already been 

 accumulated. 



In the present state of our knowledge, it is desirable to point out briefly the 

 most important facts now definitely established respecting the influence of 

 fungoid parasites upon trees and shrubs, and at the same time to call attention 

 to such unsettled questions as are specially worthy of further investigation. 

 For the sake of clearness the several classes of fungi will be considered iu 

 order. 



THE BROWK MOULDS. 



The interesting class of fungi known botanically as the Mucorini, and com- 

 monly called " brown mould,"' may be dismissed at once from our present con- 

 sideration, for the reason that they never grow upon trees, nor, in fact, upon 

 any living plants. They grow upon dead or decaying animal or vegetable 

 material, and especially upon articles of food that have been allowed to stand 



