DISEASES OF TAXODIUM AND LIBQCEDRUS. 



attachment organs as smaller portions of a hypha, formed 

 as a result of contact or pressure irritation. " These 

 organs adhere very closely to the cell- walls and in that way 

 probably act as braces to give the penetrating hypha an 

 opportunity to exert the mechanical pressure necessary to 

 penetrate the cell- wall." Miyoshi * found that in order to 

 penetrate a wall " the fixation of the hypha was absolutely 

 essential ' ' and explains the formation of attachment organs 

 as tending in that direction. Hartig f figures several cases 

 of swollen hyphae in the mycelium of Polyporus vapo- 

 rarius. 



The penetration of the cell-wall is brought about, accord- 

 ing to Brefeld,^ Biisgen (1. c.), Miyoshi (1. c.), Ward, 

 and others by the chemical action of a ferment given off by 

 the tip of the hypha, aided by pressure. In the diseased 

 wood of Taxodium the brown hyphae pass through the 

 cell-walls of the wood fibers of both spring and summer 

 wood in a radial direction. The path of a hypha is made 

 up of a succession of short curves, each within the lumen 

 of a wood cell (PL 4, fig. 1). When the tip of a hypha 

 touches the wall it is deflected considerably, as if the hypha 

 were pressing against the wall and pushing along the same. 

 At the same time the tip swells, and a thread of much 

 smaller diameter pushes into the wall. Sometimes there 

 may be two such threads (PI. 5, fig. 9). When they 

 have passed through the wall they enlarge to the former 

 size of the hypha, and grow on through the next cell, to 

 be deflected as before upon reaching the opposite wall. 

 On PL 5, fig. 9, a number of these attachment organs are 

 represented, occurring in the wood of Taxodium, and also 



* Miyoshi, Manabu. Die Durchbohrung von Membranen durch 

 Pilzfaden. (Prings., Jahrb. f. wiss. Bot. 28:269. 1895). Uber Che- 

 motropismus der Pilze. (Bot. Zg. 52 : 1. 1894.) 



t Hartig, R. Zersetzungserscheinungen, etc. pi. 8. fig. 11. 



J Brefeld, O. Untersuchungen tiber Schimmelpilze 4 : 112. /. 11, 15. 



Marshall-Ward, H. On a lily disease. (Ann. Botany 2 : 319. 1889.) 



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