868 



ZOOLOGY. 



rarely exceeds that of the water in which the fish swims by so much as 

 a degree, " so that it may be quite safely taken as an index to the latter 

 teiUiperature when there is no deep-sea thermometer at hand." 



The experiments of Dr. Kidder were made not only in the rectum and 

 stomach, but in various iiarts of the muscular tissues, the large venous 

 trunks, the cavity of the thorax after oi^euing the heart, the interior of 

 the heart, and branchial artery, and the young fish in the ovary. Although 

 Dr. Kidder admits the results to be only tentative, he considers that 

 enough has been ascertained to show that fishes do develop animal heat 

 by their own vital ])rocesses in the same manner, but in a less degree, 

 as do the higher vertebrate animals, and that they will be found to mani- 

 fest a temperature much above the water in which they swim. The 

 temperature, however, varies according to the organization and the 

 species. Thus the dog-fish {Squalus acanthias), in common with other 

 sharks, '' possessing a far more perfect digestive and circulatory sys- 

 tem than the cod, shows a much greater excess of blood tempera- 

 ture above that of the surrounding water ; and cod taken at the depth 

 of 15 fatlioms in water at 52° F., show a less excess than others taken 

 in 25 fathoms at 41° F., but a greater excess than blue-fish {Poma- 

 tomiis saltatrix (Linn.) Gill) taken at the surface, at 09° and 70°, which 

 is presumably nearer the normal temperature of the last-named fish." 



ISTinety-seven fishes, representing 16 species, were experimented upon 

 by Dr. Kidder, and, throwing out doubtful and imperfect observations, 

 the following is a summary of the results : 



' Below. 



t Above. 



THE OVARIES OF TELEOST FISHES. 



Dr. J. Brock has investigated the anatomy and histology of the organs 

 of reproduction in the male as well as female of teleost fishes.* The 



*Brock (J.). Bcitriige zur Anatomie und Histologic der Geschlechtsorgane der 

 Knockeufische. 



