339 
Marshall Ward. — On a lily- disease. 
then it seems clear that we are here concerned with a process 
depending on changes in the metabolism of the plant — the 
hyphae, under the conditions given, extrude drops of substance 
from their tips. What is this substance ? 
On examining the margins of large mycelia (from one to 
four or five inches in diameter) grown on the surface of Pasteur’s 
solution in properly sterilised flasks, I have found nearly every 
hypha extruding these drops (Fig. 44), and it was not difficult 
to obtain definite reactions. The drops react to Millon’s 
test by giving a very evident and characteristic brick-red 
colour ; nitric acid followed by ammonic hydrate results in 
the well-known golden yellow of the xantho-proteic reaction ; 
Schulze’s solution colours them yellow to yellow-brown, as 
also does iodine alone ; alcohol coagulates them, and they 
stain with such dyes as would be expected to colour pro- 
teids. 
All this, of course, would point to the drop consisting 
simply of the extruded protoplasm of the cell, and it will no 
doubt be asked why I regard it as anything else. 
For the two following reasons, I look upon these drops as 
consisting in great part of a soluble ferment which has the 
property of swelling and dissolving cellulose cell-walls ; I am 
not prepared to affirm that the drops in my cultures consist 
solely and entirely of the ferment, for it is far more probable 
that mucilage and proteids are mixed with it, and that the 
ferment only constitutes the brilliant colourless granules which 
become dissolved out from the extruded mixture of the drops. 
The two reasons upon which I lay such stress are, (1) I have 
succeeded in observing under the microscope the tips of the 
hyphae actually penetrate into and through the cellulose 
cell-walls of thin sections of lily-bulb placed in their path ; 
and ( 2 ) a watery extract of the mass of hyphae referred 
to is found to swell up cellulose cell-walls when thin sections 
are placed in drops of it. Much of the rest of the present 
paper is concerned with the elucidation of these noteworthy 
phenomena. 
But first, to make one or two further remarks concerning 
