FUNGI. 257 



and at length collect at three or four centres, which 

 condense, and ultimately are distinctly separated 

 from each other by the growth of a special envelope. 

 Finally, the membrane of the mother-cell is ruptured, 

 and the three or four smaller bodies, which have been 

 differentiated from the cell contents, make their 

 escape, each one furnished at one extremity with a 

 pair of delicate movable hairs, by means of which 

 these little bodies, now termed zoospores, can swim 

 actively in any thin film of moisture, upon which 

 they may fall. Possibly this film may be on the 

 leaf of a foster plant. In a short time all motion 

 ceases, and the zoospores come to rest, the pair of 

 delicate cilia are absorbed, and a germinating thread 

 is produced, generally from the opposite end of the 

 now quiescent zoospore, the point of which seeks out 

 and enters at one of the stomata, or pores, of the 

 sustaining plant. It must be observed here that a 

 power of selection seems to exist, for the point of 

 the germinating thread will not enter by the stomata 

 of any plant, indiscriminately, upon which it may fall, 

 but only upon such leaves as belong to the particular 

 plant, or species of plant, of which it is the recognized 

 parasite. Or even, should it enter the pore of an 

 alien plant, the thread develops no further, and no 

 infection takes place. Having once obtained an 

 entrance, the thread grows vigorously, and a little 

 mass of threads, called a mycelium, is soon developed 

 within the tissues, capable of spreading itself through 

 the plant which it has infected. In this way young 

 seedlings are infected by means of conidia from old 

 and diseased plants, or clean plants of greater 



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