No. 1.] HARDENING REAGENTS. 155 
It will be at once seen, that alcohol reduces the weight of 
the hardened specimen in the same way that it does that of a 
fresh one, and that while alcohol under 80% can produce a 
considerable loss of weight, due principally to shrinkage, the 
higher grades may also extract nearly } of the total solids. 
Section II. — Shark’s Brain. 
During the summer of 18g0, the facilities offered by the 
Marine Biological Station at Wood’s Holl, enabled us to test 
some of these reactions on the brains of several specimens of 
shark. 
The subjoined Tables 31-33 give the principal results, and 
indicate that the reaction of the shark’s brain is similar to that 
of the sheep. 
TABLE 31. 
Average of two specimens, Galeus canis,— average fresh weight — 7.05 grm. 
Fresh in 24% solution of bichromate of potash. 
Ditto 6.05 grm. allowed to stand in a covered dish for 36 hours, then put into 
2}% solution of bichromate of potash. Mean daily temperature, 21.6° C. 
Piet aWAGe PERCENTAGE INCREASE. PERCENTAGE DECREASE 
FRESH. STALE. 
| 
0.9 39-4 — 2% 
23 47-4 
Tee 49.2 2: 
18.9 49.0 a2 
338. 47-1 5:5 
432-1 46.3 B35 
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