1872.] OF THE BLOOD OF THE SALMONIDiE. 835 



those of the Sturgeon — a cartilaginous fish — that it would be difficult 

 to distinguish them, and are approached in magnitude by those only 

 of the common fresh-water Eel among the osseous fishes of which 1 

 have examined the blood. It is remarkable that in this Eel the 

 corpuscles are larger than in its bigger congener the Conger, and 

 that in the Herring they are smaller than in its near ally the 

 Pilchard ; and how nearly the red corpuscles of the river-Eel agree 

 in size with those of the Sturgeon may be seen by my figures in the 

 'Proceedings of the Zoological Society,' 1862, already cited. Were 

 the red blood-corpuscle of the Salmon duly placed as regards size, it 

 would be between the like corpuscles of Anguilla and Sturio in that 

 engraving. The further increase in the magnitude of the red 

 corpuscles of the Plagiostomes has been well known from Hewson's 

 discovery, a century since, of this fact in the Rays, to the recent 

 extension of observations in the same order of fishes by Rudolph 

 Wagner. In Lepidosiren, as I have long since shown, the blood- 

 disks are so much larger as to present rather a batrachian than 

 piscine character. 



As regards the class of fishes, we are much in want of further 

 observations ; for the corpuscles have yet been examined in only a 

 limited number of species and families. And the inquiry is especially 

 difficult in osseous fishes, since their red corpuscles are much prone 

 to very rapid changes both in size and form, and require great care 

 in the preparation. Their size varies too, still more than in the 

 hot-blooded vertebrates and scaly Reptiles, in the same species and 

 in the same individual of that species. In the Appendix, p. 3, of the 

 English version of Gerber's ' General and Minute Anatomy,' 8vo, 

 Lond., 1842, I have noticed such facts in Mammalia and Birds, and 

 Dr. Bowerbank's observations to the same effect in man. While in 

 certain members of Acanthopteri and other ichthyic orders the 

 blood-disks are like in their oval shape to the typical ones of 

 Birds, there are Fishes among the Anacanthini, Lophobranchii, &c. 

 in which the majority of the blood-disks are suboval, with some of 

 every intermediate form to a regular circle, and all this in one species 

 or a single individual. Besides, the red corpuscles often present 

 many (crescentic, fusiform, bent, angular, and other) figures, which 

 may be due to changes after death, as such forms prevail in the blood 

 of the Gadidce, &c. obtained from inland fishmongers, but not in that 

 taken with due care from living species of the same fish. Still in the 

 live fish some of these forms may be seen, anon assuming the regular 

 figure, in the red corpuscles circulating within the blood-vessels. 



Thus far concerning the irregularities in size and shape. And as 

 to the regular figures and average sizes of the red blood-corpuscles, 

 they are shown by the annexed woodcut in four species, each 



