164 BOTANICAL GAZETTE [MARCH . 
a slight swelling of this kind with Botrytis on Tradescantia, 
Mnium, etc., but Ward (35) observed with the same fungus 
(apparently), which produced the lily disease he described, such 
an extraordinary swelling of the walls of the host that a large 
part of the lumen of the cells was filled. Nordhausen believes 
that Botrytis lives on the protoplasm of the poisoned cells 
chiefly. Ward is of the opinion that the fungus causing the 
lily-disease lives also on the gelatinized walls. Erysiphe appears 
to produce not so much a swelling of the wall of the cell as the 
addition of new material to its inner surface, for the collar of 
the haustorium, formed from a part of this thickening, is dense 
and remains as a permanent structure in the cell. 
At the same time that the wall of the cell is thickening, 
growth of the penetrating tube is proceeding. Its distal end 
enters the wall, and, just at the point where the reddening of the 
wall originally appeared (fig. 2) a very slight enlargement of 
the tube occurs, accompanied still by the reddening on each side 
(in longitudinal section). But this effort does not bring the point 
of the tube into the lumen of the cell, for the thickening of the 
wall keeps pace for a time with the growth of the tube. This 
tube is extremely minute. For Botrytis Nordhausen (23, p. 39) 
found it to be one fourth of the diameter of the ordinary hyphae. 
Miyoshi (22)? has shown that the membrane to be penetrated 
affects the size of the tubes. Thus, when collodion was used 
for a membrane, the tubes actually increased in diameter, while 
with an onion skin there was no change in the size of the tube. 
Ward’s observations on this point agree with Nordhausen’s. In 
all of the Erysiphee the tube is much smaller, as the figures 
show, and it is interesting to note that the nucleus of the absorb- 
ing organ must in some manner make its way through this 
minute passage. 
The tube (fig. 3) continues its growth through the increas 
ing or (as Ward thinks for Botrytis) swelling cellulose, a part of 
which remains permanently encircling the neck of the mature 
° 3 be t. 
2 Die Durchborung von Membranen durch Pilzfaden. Jahrb. f. wiss. Bo 
30: 280. 1895. 
