EFFECTS UPON FISHES OF CHANGES IN SALINITY OF WATER. 95 



Which of the luuitiiiy niemhraiies of the liody ure thus concerned will l)e considered 

 later. 



Fredericq (1885) states that the blood of salt-water fishes tastes scarcely more 

 salt than that of fresh-water ones. Surely this is hardly an exact quantitative test. 

 H(^ repeats (Isitl) that it is "not much more salt." Fredericq likewise states (1885) 

 tliat it has long- been known that the muscles and glands of a salt-water tish are not 

 moll' salt than tiiosc of a fresh-water one. 1 can not lind upon whose authority this 

 statement is l)aseil. (triffiths (189^) makes the equally nnsupi)orted assertion that 

 ••the blood of a sole, a haddock, and a weever does not contain more soluble salts 

 than the 1)lood of fresh-water fishes" (p. 14u). 



Atwatcr (is'.tl) gives the percentage of chlorine in the fiesh of two salt-water 

 -["■lies analyzed by him as follows: Black-fish {Tautoga oiiitis) (i.2:-'>, mackerel 

 (.Sro,i,li,r sr,,iiihni.-<) 0.24; mean, 0.235. 



Three fresh-water fishes" gave the following percentages: Salmon (Penobscot 

 River— spent) 0.18; salmon (landlocked --spent) 0.20; shad (Connecticut River) o.22; 

 mean, o.2o. 



It thus appeal's from the figures of Atwatcr that the flesh of the fresh-water 

 fishes analyzed by him had about 15 per cent less chlorine than that of the salt-svater 

 ones. In comparing his percentages just quoted with mine it must be remembered 

 that Atwatcr used the flesh alone while I used the entire fish, including the skeleton. 

 The proportion of chlorides in the latter we should expect to be smaller than in the 

 flesh. 



The figures given by Almen (cited by Atwater) show such enormous difierences 

 in the amounts of chlorine in different fishes (his maximum figure being nearly 15 

 times as great as his minimum) that they are certainly to be regarded with suspicion. 

 It may be noted, however, that the average figure for salt-water species is much 

 higher than that for the fresh-water ones (0.122 and 0.076, respectively, provided 

 that \vc count the salmon and eel among the fresh-water ones). 



Katz (!--;••■,) gives the mean percentage of chlorine in the dorsal muscles of 2 

 large ccK (apiiarently from freshwater) analyzed by him as 0.034-18; the mean figure 

 for 2 pike was 0.03191; that for 2 haddock ('' Schelltisch") was 0.24093. Such 

 results certainly demand confirmation. It may be noted that Almen's figures for the 

 eel and pike were 0.013 and 0.186, respectively. 



Church (1903) states that he found 0.2 per cent of "common salt" in a ■"mack- 

 erel in good condition." This would place the percentage of chlorine at about 0.121. 

 Atwater's figure was almost exactly twice as great. 



As regards the salinity of the blood, the determinations of Quinton (litol, pp. 

 439—140) give the mean percentage of chlorine'' in the blood of 8 species of marine 

 teleosts as 0.651, that for 3 fresh-water species as 0.411. From these figures it 

 would appear (1) that the salinity (at least the proportion of chlorine) of the blood 

 is several times that of the body as a whole, and (2) that the salinity is over 50 per 

 cent greater for salt-water than for fresh-water species. Mosso (1890) likewise 

 states that sea fish have moi'e salt in their blood than fresh-water ones, though he 

 offers no figures in support. 



<i The shad and the Atlantic salmon are of course anatlromous, but the present specimens appear to liave been taJjen 

 in Iresh water. 



frQuinton's original figures are given in terms ot Nat'l, but I have reduced them to corresponding values ni clilorine. 



