214 Experiments on the Growth of Yeast. [Sess. 3 
it, the flanges not being properly caulked and cemented. The 
result was that the roots of a chestnut-tree which grew near 
had found their way into the pipes and ran along in a most 
remarkable manner. The exact distance the roots extended 
% 
in the pipes was unfortunately not measured, but it is safe to — 
put it at over a dozen yards. So effectually had they filled 
the drain that some of the pipes could not be removed without 
breaking them, when there was revealed a cylindrical mass — 
of matted roots, showing in a perfect manner the formation 
of the flanges of the pipe. It would have been interesting 
to have had the entire length taken out intact, but as the 
labourers were anxious to save the pipes, the roots were cut 
asunder at every three feet. So solid had they become that 
even a three-feet length was a considerable weight, resembling 
pretty closely a “divot” without the green grass on the out- 
side. One would have liked to ascertain how far the roots 
would have travelled along the drain had they been allowed | 
to remain. Personally I am of opinion they would have 
grown a long distance. Thinking it might be interesting, I 
have brought the “ tail end” of the growth for exhibition here — 
to-night. I am aware that in narrating this case I am re- 
iterating a simple statement of a well-authenticated fact, but — 
though the fact is well known, it is seldom that an illustration 
is brought under the notice of others than contractors and 
their labourers. 
XIII—NOTES OF EXPERIMENTS ON THE GROWTH ‘ 
OF YEAST IN SOLUTIONS OF ARSENIOUS 
OXIDE OF VARIOUS STRENGTHS. 
By Mr W, C. CRAWFORD, F.R.S.E., anp Dr A. E. DAVIES. 
(Read April 24, 1901.) 
AT the meeting of the British Association last year, after Major ] 
Ross had given a lecture on Mosquitoes and Malaria, in which 
he traced the life-history of the hemamceba from man through | 
the tissues of its other host, the mosquito, and back again to 
