No. I.] HARDENING REAGENTS. 
139 
In this latter case, the brain substance bulges out at the 
slits in a way which suggests that it has been restrained in 
swelling by the action of the surrounding membrane. 
Influence of Slits. — The matter was repeatedly tested in this 
way. <A series of encephala were carefully removed with the 
pia intact ; then half the number of specimens were slit with 
a scalpel, so as to largely do away with the restraining action 
of the pia. In the first series six encephala were taken, — 
three intact, three slit. 
At the end of 48 days, in a 2% solution of bichromate of 
potash, we have the following : — 
TABLE 12. 
SERIES TI. 
Percentage increase in weight at the end of 48 days: — 
BRAIN WITHOUT SLITS. 
BRAIN WITH SLITs. 
28.9 36.8 
26.4 338 
32.0 38.6 
Average = 29.1 Average = 36.4 
Excess) ——" 7-3 
SERIES II. 
At the end of 24 days : — 
27-4 37-4 
32.0 39-6 
26.9 36.1 
Average = 28.8 Average, == 37.7 
Excess ——) 75)(0) 
SERIES IIT. 
AFTER 8 Days. AFTER 24 Days. AFTER 41 Days. 
Encephala without slits .. eh 34.6 35:7 
l 27 34-7 36.2 
Average ..... ——27-0 == 34.0 ONO 
