CRYOSCOPIC AND OSMOTIC DATA. 85 



fact that the land turtles do not show a more concentrated blood 

 than do those which live mainly in fresh water. 



This point was put to the experimental test upon the marine 

 turtles, Colpochelys kempi and Caretta caretta; the last figure in 

 the previous data given above for each of these species was ob- 

 tained, with the blood of a specimen which had been kept for 

 two months in a tank containing fresh water. There was ab- 

 solutely no change in the concentration of the blood of these 

 individuals, and we feel justified in concluding that adjustments 

 of the nature of those under consideration do not take place in 

 these forms at least not within the duration of our experiments. 



(d) Fresh Water Fish. — Preliminary to a study of the effects 

 of osmotic and saline media upon fresh water fish (soon forth- 

 coming) it was desirable to know the osmotic pressure of the 

 blood of forms taken from the Mississippi river. The following 

 list contains some forms peculiar to this region on which no data 

 have hitherto been given. 



1. Polyodon spathula = — 0.492°, — 0.486°, — 0.50° C. 



2. Scaphirhynchus platyrhynchus = — 0.505°, — 0.507°, — 0.503° C. 



3. Lepidosteus osseous (L.). ("Gar") = ~ 0.487° to — 0.52° C. 



4. Amia calva (L.) (land locked) = — 0.508° C. 



5. Catostomus teres = — 0.51° to — 0.52° C. 



6. Perca fluviatilis = — 0.498° to — 0.51° C. 



Fresh water ganoids are seen to have blood which is identical 

 in concentration with that of fresh water teleosts. All have blood 

 less concentrated than that of any of the marine fishes and it is 

 conceivable that in the case of these animals some adjustment to 

 environment has taken place; such adjustments are known for 

 marine fish as has been shown by the author (i) and others (Fred- 

 ericq, Bottazzi, Dekhuysen (8), Dakin, loc. cit.). 



REFERENCES. 



1. Garrey, Walter E. 



'05 Biol. Bull., VIII., p. 257. 



2. Loeb, J. 



'13 "Artificial Parthenogenesis" Chicago, p. 34 



3. Loeb, J. 



P. 35, loc. cit. 



4. Jones, H. C. 



'93 Zeitschr. f. Physikalische Chemie. — XII, pp. no and 529; XII., p. 623. 



