3i8 Journal of Comparative Neurology. 



III. Post-mortem Changes in the Weight of the Central Nervous 



System. 



During the first twenty-four hours after death the central 

 nervous system of a frog killed by ether or chloroform ex- 

 hibits a remarkable power of absorbing water from the sur- 

 rounding tissues. 



During the month of August the frogs, which are given in 

 Table 5, were weighed, then killed and the legs removed and 

 examined at once. The remainder of the frog was kept cold in 

 a refrigerator for twenty-four hours and at the end of that time 

 the brain and spinal cord were removed and weighed. The re- 

 sults are here given : 



TABLE 5. 



After Twenty- Foitr Hours. 



Fresh Body-weight Weight of Brain Weight of Spinal 



in grams. in grams. Cord in grams. 



265 .303 .150 



271 .302 .I4I 



293 -303 -149 



Average 276 .303 .146 



No. 51C. 272 .202 .104 



Amount of difference= Brain 50^/^,. Cord=40^, 



At the end of the Table the average of the cases examined 

 twenty four hours after death is compared with a normal record 

 (No. 51C, Table 7), and it is seen that there has been an in- 

 crease in weight of about 50% in the brain and 40% in the 

 cord, over and above the normal. There is no reason for insist- 

 ing here on the constancy of exactly this amount of change, nor 

 have I made experiments to determine in what manner it occurs, 

 but it is evident that when left in the body for a day or more 

 after death the central nervous system of the frog tends to 

 increase in weight, and hence all examinations of it should be 

 made as speedily as possible. 



IV. Influence ok Water Absorbed by the Living Frog on the Weight 

 of the Brain and Spinal Cord. 



This capacity for change post-mortem as just described, 

 would naturally suggest that normally the central nervous system 



