No. 1.] HARDENING REAGENTS. 125 
work was carried on in the Pathological Laboratory of the 
New York Hospital. During that time we were indebted to a 
number of physicians in New York for material placed at our 
disposal. 
During the winter of 1890-91, Dr. J. C. Cardwell and Prof. 
C. F. Hodge both took an active share in the observations ; 
and the former made several independent series of tests which 
he kindly permits us to use. Since October, 1892, the work 
has been carried on in the Neurological Laboratory of the 
University of Chicago, and in its completion Mr. A. C. 
Eycleshymer has taken part. 
Outline of Observations. — Our notes at date enable us to 
speak in some detail concerning the effects of the solutions of 
bichromate of potash and of alcohol on the weight, the volume 
and percentage of solids in the brain of the sheep, and ina 
more general way, concerning the effects of these and some 
other solutions on the brains of sharks and men as well. 
SecTION I, — Sheep's Brains. 
The results obtained can perhaps be most simply presented 
by following the history in a typical case and then noting the 
effects of varying the conditions which are there imposed. 
Typical Case.—If the entire encephalon of a sheep is 
removed from the cranium some six hours after death, the 
animal having been killed by bleeding, it will be found that it 
can be taken out with comparative ease, if the hypophysis and 
the gray caps of the olfactory bulbs are neglected. This was 
the case in the brain of which we speak. The pia was always 
left on the brain. 
After removal, the brain was cut longitudinally, thus giving 
two symmetrical halves (hemiencephala) approximately equal 
in weight. 
The first experiments were made on hemiencephala of the 
sheep. Since each half of the encephalon contained the same 
proportion of the different encephalic structures, it was possible 
by this means to make two tests with the brain of one sheep. 
