392 ‘Dr. H. Charlton Bastian on the Origin 
tox the stain freely, as may be seen by Pl. XXV. fig. 3, B> 
x 500). 
In November, 1900, a small new potato had been treated in 
the same manner that I have already described, but after 
pouring away the 10 per cent. formalin solution the bottle 
was filled with carbonic acid gas before screwing on the top *. 
This bottle was then placed within an incubator and allowed 
to remain there at a temperature of 84° F. for six weeks. 
On examination the appearance of the potato externally 
and internally was almost exactly such as I have described in 
the others. There was the same mottled colour of the cut 
surface, with a rather deeper tint in the centre as well as in 
some other parts. 
Sections of the central portions of the potato were made and 
placed for a short time in a carbo-fuchsine solution. On 
microscopical examination in many of the cells very small 
mycelial filaments (something like Crenothria filaments), with 
spore-like bodies at intervals, were found, such as are shown in 
Pl. XXV. fig.4,B (x 500). The filaments were lying on the 
primordial utricle, and, as in many other cases, the organisms 
had scarcely taken the stain at all. In other cells what 
seemed like the beginnings of such organisms, or of others 
very similar, were found on the surface of the primordial 
utricle, as shown in Pl. XXV. fig. 4, A (x 500). 
At the end of March 1903 I made another slight variation 
in the conditions, and again obtained a rather different result. 
A small new potato, after careful washing, was placed in a 
small tin with avery tightly fitting cover and allowed to soak 
in 10 per cent. formalin for twenty minutes, the fluid having 
been shaken about several times so as thoroughly to wet the 
whole internal surface of the tin. . The fluid was then poured 
off, leaving the surfaces wet with the solution as before; the 
tin cover was very tightly jammed down and the vessel was 
again placed within a copper incubator at a temperature of 
75° F., and allowed to remain there for eight weeks. 
When taken out and examined the cut surface of this potato 
presented just the same characters as in the others: the whole 
substance was firm throughout, there was no shrinking, and 
the central portion was rather darker than the other parts, 
which showed the usual mottling. 
Sections were made, shaken up in distilled water in a small 
tube as before, and then placed for a short time in a dilute 
gentian-violet solution. On microscopical examination a 
* The filling the vessel with CO, was a method adopted by Pasteur 
in his experiments on the fermentation occurring in fruits contained in 
closed vessels, 
