40 ANNALS NEW YORK ACADEMY OF SCIENCES 



Experiment 3. Carcliarias Uttoralis. Female. 48 inches long. 



No laking in 2.0 per cent NaCl to 1.2 per cent NaCl. Faint trace in 1.0 

 per cent NaCl. Decided in 0.8 per cent NaCl. 

 Experiment 4. Raia erinacea. Female. 20 inches long. 



No laking in 2.0 per cent NaCl to 1.2 per cent NaCl. Faint trace in 1.0 

 per cent NaCl. Decided in 0.8 per cent NaCl. 



It is clear that Mosso's statement is not applicable to the elasmo- 

 "branchs from the Woods Hole region. In the case of the four species here 

 indicated, there is no laking down to the 1.0 per cent NaCl solution and 

 even this dilution does not decidedly lake the blood. Bottazzi ('06) found 

 that the blood of elasmobranchs at N"aples was more resistant than Mosso 

 •claimed; the first solution to lake the corpuscles was approximately a 2.0 

 per cent to 1.75 per cent solution of NaCl. Rodier ('99) found that elas- 

 mobranchs at Arcachon lost the haemoglobin of their corpuscles in less di- 

 lute solutions than Mosso found to be the case with the elasmobranchs at 

 Naples. Bottazzi ('06) explained this difference as being due to the dif- 

 ference in the salinity of the water at the two places. Thus the A of the 

 sea-water at Naples is 2.29°, while the A of the sea-water at Arcachon is 

 2.00°. The average concentration of the laking solutions at Arcachon 

 was 1.46 per cent NaCl. It appears that the corpuscles of the elasmo- 

 branchs at "Woods Hole are much more resistant than those at Naples or 

 at Arcachon, and more resistant than can be accounted for by the differ- 

 ence in the salinity of waters. Eodier ('99) believed that the urea in 

 elasmobranch blood had something to do with the difference in the 

 haemolytic relations of elasmobranch and teleost blood; but Bottazzi ('99) 

 found that even in a 6 per cent solution of urea which is almost isotonic 

 with the blood the corpuscles lost their haemoglobin. He came to the con- 

 clusion that in addition to the osmotic pressure exerted by the substances 

 dissolved in the blood each of these substances and especially the sodium 

 chloride exerted a specific chemical effect upon the corpuscles, thus main- 

 taining their integrity. I made up a second series of solutions containing 

 the same percentage of sodium chloride as the preceding series, but in 

 addition each solution contained as much urea as NaCl, for the reason 

 that elasmobranch blood contains about the same amount of urea as salts. 

 In each case the corpuscles appeared at first sight to be more resistant in 

 the solution of NaCl and urea than in the NaCl solutions. This is as 

 follows : 



Mustelus canis — Corpuscles laked in 0.8 per cent NaCl and 0.6 per cent 



NaCl -f urea. 

 Squalus acanthias — Corpuscles laked in 0.6 per cent NaCl and 0.4 per 



cent NaCl -f- urea. 



