454 BULLETIN OF THE BUREAU OF FISHERIES. 



respectively, or a decrease of 3.3 per cent for brackish- water salmon and 17.6 per 

 cent for spawning-ground salmon. This decrease of lT.ti per cent in blood concen- 

 tration is very significant from two very different points of view. First, because the 

 change is as small as it is, considered in relation to so profound a change in environment 

 as that represented by a passage from sea water to fresh water. This change made 

 suddenly is well known to be fatal to many sea forms. The cyclostome Polistotrema 

 stouti," when transferred to sea water diluted one-half with fresh water, dies in a few 

 minutes with violent swimming and struggling. The blood of this cyclostome, 

 however, has a concentration about the same as that of the sea water in which it 

 lives. In three samples determined in July, 1901, the average depression of the 

 freezing point for Polistotremn stouti serum is —1.966° C, as against —1.924 C. for 

 the water of Monterey Bay. in which it lives. This form can not make the transi- 

 tion suddenly, at any rate. The related lampreys are anadromous, and it will be 

 interesting to see what is the concentration of lamprey blood. Marine invertebrates 

 can not safely be transferred to fresh water. In this group, however, as Bottazzi' 

 and others have shown, the blood has the concentration of sea water. Quinton'' 

 found that the blood of marine invertebrates takes the concentration of the bathing 

 liquid when placed in water of greater or less concentration than sea water — that 

 is, that the skins are permeable to both salts and water. Garrey'' has just shown 

 that blood or body fluids of certain marine invertebrates varies not more than 

 0.02° C. in its freezing point from that of the water in which they live. He tested 

 the following: Thyone briareus, Arbacia picnctulata, Asterias vulgaris, Sycotypus 

 rthHtl ifiiliifus, Venus mcrri'iiitriii. Mt/ti urinaria, Homarus america/nus, and LimuVus 

 pobyph. in us. He also shows that the external tissues of these animals are permeable. 

 Mosso' found that sharks {Scyllium) transferred to fresh water died within an hour. 

 In fact, the circulation ceased at the end of one-half hour, though the heart still 

 contracted, the blocking of the circulation being due to clogging of the vessels of 

 the gills. Bottazzi also points out that in marine bony fishes the blood has a far less 

 concentration than in invertebrates or in cartilaginous fishes, a fact which I can 

 confirm for all three groups. He makes the point that bony fishes show an interme- 

 diate position in this regard between cartilaginous tishcs and air-breathing vertebrates 

 in that they have acquired a certain degree of independence of their surroundings. 

 Garrey was unable to demonstrate permeability of the tissues of Funduhis when 

 transferred from sea water to fresh water. 



The salmon show a very decided independence in the relation between the com- 

 position of the blood and the surrounding water. Their gills and skin are imper- 

 meable — the exception, of course, being the permeability to oxygen and carbon 

 dioxide. At first thought one would be inclined to ascribe the fall of concentration 

 of the blood of 17.6 per cent to direct absorption of water in fresh water, but such 



a This interesting species has been the subject of a number of valuable physiological and morphological papers. It was 

 originally described under the name BdeUostoma stouti Cooper, and has been identified with Bddlostovm dombeyi by several 

 authors. 



b Bottazzi, La pression osmotique du sang des animaux marins. Arch. ital. de Biol. 29, 1S97, 61. 



<■ Quinton, M. R. Communication osmotique chez l'invertebres marin normal, entre le milieu interieur l'animal et le 

 milieu exterieur. Comptes Rendus, 131, 1900, 905. 



dGarrey, Walter E. Osmotic pressure of sea water and of the blood of marine animals. Biol. Bull.. VIII, 1905, 257. 



t Mosso, Inner verschiedene Resistenz der Blutkorperschen bei verschiedenen Fischarten. Biol. Centralb. Bd. 10, 1890, 

 S. 570. 



