BIOLOGY OF COLLYBIA VELUTIPES. 159 
of infected wood, striking results are obtained. The sections 
are heated to 160? C. with concentrated caustie potash in sealed 
tubes, then washed in 90 per cent. alcohol, and placed in a 
dilute solution of iodine in potassium iodide until deeply stained, 
when they are transferred to diluted sulpburic acid. The 
cellulose-walls stain a deep blue-green colour, and the chitin 
walls of the hyphe a brilliant pink. On washing rapidly in 
water the dark colouring of the cell-walls may be partially 
removed aud their swelling prevented. Sharply differentiated 
prepy :tions are obtained by this method, which may be utilized 
in t/ cing the course of the hyphæ (Pl. 4. fig. 17). 
/ n the breaking down of the cellulose layers, bundles of 
acicular crystals of calcium oxalate are formed. They stain 
deeply with hematoxylin, probably owing to the precipitation of 
proteid matter upon them by the action of alcohol. When 
treated with sulphurie acid, however, a granular deposit of caleium 
sulphate is left in their place, thus proving that they really do 
consist of the oxalate. 
On extraeting the wood with caustic potash, and so removing 
xylose-yielding substances, a peculiar change is brought about in 
the action of the fungus. ‘Transverse sections of the infected 
wood placed in chlor-zinc-iodine solution now give a cellulose 
reaction; the thickening-layers stain a deep purple colour 
and are swollen so as almost to obliterate the lumen, and in 
places they are wrinkled away from the middle lamella. These 
appearances are precisely the same as those given by wood 
infected with lignin-destroying fungi when so treated*. Similarly 
extracted, uninfected wood gives no such reaction. If however 
the wood, from which xyloses have been removed, is treated with 
a l per cent. solution of cane-sugar before infection, the action 
of the hyphe is similar to that already described as normal, and 
the lignin is left unattacked. 
It would seem, then, that soluble earbohydrates are of great 
importance in the proper nutriment of the fungus, but in their 
absence it is capable of varying its usual course of action and 
using lignin as a substitute. If we may regard this latter sub- 
stance as a glucoside, as is often done, one might assume that in 
its decomposition glucoseis produced and used by the fungus as 
à food-material. 
* Marshall Ward, Phil. Trans. vol. 189. B. (1897), p. 123. 
