28 



ANNALS NEW YORK ACADEMY OF SCIENCES 



water. A stream of fresh water was then made to flow into its mouth 

 and out through its gills. At the end of fifty minutes the freezing point 

 of the blood of this specimen, whose gills alone were exposed to the fresh 

 water, was 1.585°. As great a change had taken place in the osmotic 

 pressure of its blood as had taken place in the case of those whose gills, 

 intestinal wall and body surface were all exposed to the fresh water. 



The operation on the five following specimens was similar to that on 

 the preceding specimen. A stream of water was not conducted through 

 the mouth, but the fishes were so placed on the support that the head as 

 far back as the fifth gill slit was immersed in the water. In this manner, 

 the oesophagus being ligated and the trunk of the body being out of water, 

 the gills constituted the chief structures exposed to the experimental con- 

 ditions. More than one determination of the freezing point was made in 

 each case, the conditions of the experiments recorded in Table II being 

 thus duplicated. These five specimens were also left in the fresh water 

 until near death. The following, Table X, shows the results obtained 

 from them : 



Table X. — Change in the osmotic j^ressiire of the blood of Mustelus canis 

 caused hy immersion of the head alone in fresh water 



No. 



l^ength in 

 cm. 



Weight in 

 grams 



Immersion 

 time in 

 minutes 



/\ of blood 



Rise in A 



1 



80 



1290 





 15 

 40 

 55 



1.85° 

 1.68 

 1.52 

 1.37 



+0.000° 



+0.17 



+0.33 



+0.48 



2 



77 



1148 





 23 



85 



1.92 

 1.75 

 1.965 



+0.000 



+0.17 



+0.455 



3 



79 



1134 





 45 



85 



1.87 

 1.72 

 1.56 



+0.000 



+0.15 



+0.31 



4 



86 



2041 





 35 



87 



1.93 

 1.81 

 1.59 



+0.000 



+0.12 



4-0.31 



5 



80 



1616 





 33 

 93 



1.925 

 1.835 

 1.475 



+0.000 



+0.09 



+0.45 



The maximal changes in the freezing point of the blood in the case of 

 the specimens belonging to Table YII, in which the three factors, body 

 surface, intestinal wall and gills were exposed to fresh water, were, 

 respectively: +0.33°, +0.43°, +0.445°, +0.37°, +0.27°, +0.50°, 



