in the Hymenomycetes. 495 
division. I am indebted to Professor Marcus Hartog, however, 
for a method of staining, not yet published, which gives 
beautiful results, and I take this opportunity of thanking him 
for his kindness. I am not at liberty to give here the exact 
method employed, but it will suffice to state that two stains 
are used, Mayer’s alcoholic solution of carmine and a strong 
acetic solution of nigrosin. By this method I have been able 
to demonstrate satisfactorily not only the structure of the 
nucleus but also the various stages in the process of its 
division, and I have also obtained a double staining of the 
nucleus in which the nucleolus becomes bluish-red, the net- 
work and nuclear membrane blue. The cytoplasm at the 
same time becomes red or reddish-blue. 
The sections were examined with the apochromatic object- 
glasses of Zeiss, of which I have used the 1*3 aper. % mm., 
i*4 aper. 2 mm., and 1*3 aper. 1-5 mm. with oculars 8, 12, and 
18, and a sub-stage condenser of high angular aperture made 
especially for high-power lenses by Swift. It is necessary to 
pay considerable attention to the illumination of the object in 
using these high powers. The best light is obtained from the 
edge of the flame of a paraffin lamp, with a metal chimney 
covered with some dead-black material on the inside. This is 
preferable even to the best daylight. 
Structure of the Basidia. 
If sections through a moderately young pileus of Agaricus 
stercorarius or A. [Amanita) muscarius be examined, they will 
be found to exhibit basidia in all stages of development. The 
basidia of the two species differ considerably in appearance 
owing to difference in density of their respective protoplasm. 
In Agaricus stercorarius the protoplasm is dense and granular, 
stains very deeply, and possesses but few or no vacuoles. The 
protoplasm in A. muscarius , on the other hand, is at no time 
very dense and, except in the very young stages, is generally 
full of vacuoles. The latter species is therefore a much more 
favourable object for the examination of the details of nuclear 
