SCOTT, STUDY OF CHANGES IN MUSTELUS CAN IS 67 



of the blood should undergo a similar reduction of 15.5 per cent of 

 — 1.02°, or 0.158°. If the salts are diluted to the same extent as the 

 organic substances, there should be an additional rise in the freezing 

 point equal to 15.5 per cent of — 0.85°, or — 0.132°. This would make 

 the total change in the freezing point of the blood due to immersion in 

 fresh water equal to 0.29°, but, as a matter of fact, a rise of 0.408° was 

 noted on page 14. In other words, the change in the freezing point due 

 to dilution alone does not account for the maximum change observed by 

 actual experiment. How can the remainder of the change be accounted 

 for? 



The total loss in chlorine and probably in salts from the serum has 

 been shown to be 25.7 per cent. In the preceding paragraph, 15.5 per 

 cent of this loss has been ascribed to dilution. There remains 10.2 per 

 cent, or — 0.087°, which I conclude represents the amount lost by diffu- 

 sion through the gill membranes. If 0.29° rise in the freezing point be 

 due to dilution, and a further rise of 0.087° be due to diffusion, the two 

 values combined account for a total rise of 0.377°. The observed rise 

 was 0.408°. 



Dakin ('08) in discussing work of a similar nature wrote, "Another 

 interesting point in the above results is that reduction in salt contents 

 of the blood as indicated by the chlorine contents is much greater than 

 the lowering of the osmotic pressure would lead one to expect." This cait 

 now be explained in the following manner : If the loss in salts had been 

 €qual to the loss in organic substances then the percentage change in i]vi 

 freezing point would have been equal to the percentage change in these 

 other substances. Since, however, the change in the salts is in excess of 

 the change in the other substances, it follows that the percentage change 

 in the freezing point of the blood is somewhat greater than the percentage 

 change due to organic solutes and somewhat less than the percentage 

 change in the salts. This is shown by the data. Thus there was a loss 

 of 15.5 per cent in organic solutes, a loss of 25.7 per cent in salts, but 

 only a loss of 21.9 per cent in the osmotic pressure of the blood. Hence, 

 not only do the calculations of the change in the freezing point of the 

 blood based on the results of chemical analysis confirm the general result 

 ascertained, by the direct determination of the freezing point, but it is 

 also possible to gain further insight into the nature of the changes pro- 

 duced. 



It has been found that the blood is but slightly laked even at the time 

 of death in fresh water. At the same time, the ratio of the volume of 

 corpuscles to plasma increases. The corpuscles increase in volume. The 

 accompanying slight trace of laking shows that while the corpuscles as a 



