DISEASES OF TAXODIUM AND LIBOCEDRUS. 49 
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 ¢ 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,t 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 TYaxodium 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 
Pilzfiden. (Prings., Jahrb. f. wiss. Bot. 28 ; 269. 1895).—Uber Che- 
motropismus der Pilze. (Bot. Zg.52:1. 1894.) 
+ Hartig, R. Zersetzungserscheinungen, etc. pl. 8. fig. 11. 
+t Brefeld, O. Untersuchungen iiber Schimmelpilze 4: 112. f. 77, 15. 
§ Marshall-Ward, H. Ona lily disease. (Ann. Botany 23319. 1889.) 
4 27 
