GENERAL I NTR4 >l M'< TH >N 



THE STRUCTURE OF AGARIl S 



Aii Agaric is a plant which, considered morphologically ami 

 physiologically, is composed <>f two portions: the vegetative, called 

 the mycelium', the reproductive, called the fruit body or carpophore. 



Tin- Mycelium 



When a spore, derived from the .uills of a fruit-body, germina 

 it forms a protuberance on one or more sides; this elongates into the 

 form of a filament, always growing a1 the apex ami usually branch- 

 ing abundantly, so thai finally a weft or mass of such becomes 

 visible, even to the naked eye. The filaments thus formed are r<- 

 ferred to as hyphae, or collectively as mycelium. In diameter they 

 vary from :'. to <> thousandths of a millimetre ami singly can be 

 seen only with the microscope. Cross-partitions are numerous ami 

 the separate divisions are the ultimate units of structure, i. <■.. the 

 cells. Such mycelium is widely distributed in the soil, humus. 

 decaying wood. etc.. and once established is doubtless perennial, 

 so that new supplies from spores are probably less common than 

 ordinarily supposed. It absorbs its food directly through tin- deli- 

 cate cell-walls and the interior of each cell is thoroughly saturated 

 with water. It appeals capable of withstanding considerable dry- 

 ing, perhaps for long periods, reviving ami renewing it^ growth 

 alter receiving a new supply of moisture. In some cases the 

 mycelium twines itself into strands which become dark colored 

 ami tough and which are spoken of as rhizomorphs ; or minute 

 tuber-like masses may he formed, termed sclerotia. These evidently 

 also serve as a resting sta^e during dry weather. The mycelium is 

 usually hyaline under the microscope, hut massed together appears 

 whitish to the eye; it may also have other colors, green, blue, red, 

 yellow, etc.. hut these are not very common. When growing lux 

 uriantly in artificial beds of manure it becomes the "spawn" of com 



menial mushroom growers. Methods are now in use in laboratories 



by which many kinds of spores are germinated and the mycelium 



grown in pure cultures; the "spawn" obtained in this way is called 

 •'pure culture spawn." 



The distribution of the mycelium in an undisturbed soil, as for 



