THE DENSITY OF WATER AND THE BLOOD OF FISHES. II49 



In conclusion it may be said that when fishes are kept in fresh water there 

 is a decrease in the number of corpuscles per cubic millimeter, a lowering of the 

 hemoglobin percentage, a lowering of the specific gravity, and a lessening of the 

 depression of the freezing point, all of which shows a dilution of the blood. 

 But, on the other hand, is there shown a concentration of the blood when fishes 

 are placed in a more dense medium? In the case of 19 Fundulus heteroclitus 

 kept in sea water, the density of which was increased to about i .040 by the addi- 

 tion of 25 grams of sea salt to each 1,000 of sea water, the average percentage of 

 hemoglobin was found to be 77 per cent, as compared with 51 + per cent in the 

 case of 18 normal fishes. 



As to the number of corpuscles per cubic millimeter, the following experi- 

 ment was devised: The average number of corpuscles in 8 individuals has been 

 found to be 2,749,000 per cubic millimeter. A fish placed for an hour in a solu- 

 tion of sea water and sea salt so that the specific gravity was 1.050 showed a 

 corpuscle count of 3,072,000 per cubic millimeter. After 2}4 hours immer- 

 sion in sea water and sea salt whose specific gravity was 1.068 the corpuscle 

 count of another specimen was 3,912,000 per cubic millimeter. The average 

 blood count of 1 4 Fundulus heteroclitus kept in a solution of sea water to every 

 liter of which was added 25 grams of sea salt was found to be 3,539,000, while in 

 another case the blood count of two fishes in a solution of sea water to every 

 liter of which was added 45 grams of sea salt was found to be 4,217,000 per 

 cubic millimeter. 



At the same time in another experiment record was kept of the weight of 

 the fishes and it was found that they lost steadily in weight while the corpuscle 

 count increased. The same general results were obtained in all the experiments 

 of this nature. From a great many experiments I can corroborate the state- 

 ment of Sumner as to loss in weight when placed in more dense solutions. As 

 to the change in specific gravity, fishes taken at the same time as those used in 

 getting the normal specific gravity were experimented upon. On placing a lot 

 of 10 in a solution of sea water and sea salt to raise the specific gravity to 1.045 

 for a period of nearly three hours, the specific gravity of the blood was found to 

 be 1.054. During that time the fishes had lost 7.5 per cent in weight. On 

 remaining in same solution nearly six hours, the average specific gravity was 

 1.060 and the fishes had lost 1 1 per cent in weight. 



In another experiment with a solution of 1.040 specific gravity there was 

 noted a gradual increase in specific gravity of the blood during the first day. 

 This increase persisted in the case of those examined during the next day, while 

 in 8 specimens examined two days later there was a decrease toward normal in 

 the specific gravity noted. Although this one experiment is inconclusive, it 

 indicates a reaction toward the normal. There is such a thing as normal specific 

 gravity of the blood, and any marked departure is pathological. Hence the 



