268 WALTER E. CARREY. 



crease the osmotic pressure of the blood. In consequence of 

 such an event we would expect nutritional changes and possibly 

 a disintegration of the red blood corpuscles. Such a disinte- 

 gration in many marine teleosts has been described though the 

 resistance of blood corpuscles of the migratory fish seems to be 

 very much greater than of other forms offish, for they lose their 

 haemoglobin only in salt solutions containing as low as 0.3-0.4 

 per cent, sodium chloride (Mosso 17 ). 



The maintenance of an osmotic pressure lower than that of 

 the sea water speaks for a relative impermeability of all the mem- 

 branes of marine teleosts. The experiments we have described 

 indicate an absolute impermeability of the integument. It may 

 riot be assumed that all the membranes are absolutely impermea- 

 ble nor is there the same degree of impermeability in all teleosts 

 as is indicated by the great variation in the resistance of marine 

 teleosts to changes in the osmotic pressure of the aquarium water. 

 Loeb's u experiments with Fiuiditlns on the poisonous effects of 

 sodium chloride indicate a certain degree of permeability of some 

 surface. The poisonous action of heavy metallic salts, of acids, 

 and alkalis indicate the same fact although many other factors 

 must be taken into consideration among which is a possible and 

 probable alteration of permeability due to these chemicals. A 

 certain degree of permeability of young Fundnlus is prettily 

 shown by immersing them in sea water containing the merest 

 trace of colored salts, such as salts of copper, cobalt and man- 

 ganese. In these cases the solution may be almost colorless 

 but in time the living embryos may become very deeply colored. 



The facts indicate the probability of some regulative mechanism 

 among teleosts (Hober I3 ) the existence of which has not yet been 

 demonstrated, and the nature of which cannot be affirmed. 



SUMMARY. 



1. The sea water at Woods Hole, Mass., freezes at 1.82 C, 

 at Pacific Grove, Cal., J is 1.90 C. 



2. The blood or body fluid of a marine invertebrate has the 

 same freezing point as the sea water from which it is taken, and 

 therefore has the same osmotic pressure. This is also true of 

 selachian blood, although the salt content is lower than that of 



