64 SPECIFICITY OF THE BLOOD OF VERTEBRATES 



substances than hemocyanin may exhibit a variety of colors, which colors 

 may be properties of the plasma or corpuscles or both. Even among animals 

 of a given subkingdom the coloring matter may differ very much. Thus, 

 among Annelida, as stated, certain bloods are red owing to hemoglobin; 

 in others the coloration tends to a reddish-brown owing to echinochrome ; 

 while in others it is green owing to chlorocruorin, etc. Among the Arthro- 

 poda we may find hemoglobin, hemocyanin, pinnaglobin, or other pigment 

 present. In Insecta we never find hemocyanin, and rarely hemoglobin; 

 in Crustacea there may be hemocyanin or hemoglobin; in Decapoda and 

 Stomatopoda the blood coloring matter is hemocyanin ; while in Cladocera, 

 Phyllopoda, Copepoda, and Ostracoda there is hemoglobin. Among Mol- 

 lusca, in some the blood is colorless; in others is found pinnaglobulin, 

 which is closely related to hemoglobin, containing manganese in place of 

 iron; in some there is hemoglobin; but in most of them the coloring matter 

 is hemocyanin. In Gasteropoda and Cephalopoda hemocyanin is present. 

 In the Chcetopoda hemoglobin has been found in quite a number of species, 

 and chlorocruorin in a few. In Gephyrea, Nemertina, and Hirudinea hemo- 

 globin has been noted. 



In Insecta the blood may be colorless or of various colors, but is usually 

 colorless. The coloration is a property of the blood plasma, and except the 

 blood of the larva of the dipterous insect Chironomus and Mitsca domestica 

 there appears to be an absolute absence of hemoglobin from the bloods of 

 these animals, although histohematins and myohematins have been found 

 in various of the body structures of a number of them. 



In all the invertebrates which have hemocyanin this substance is, as 

 far as known, in solution in the blood plasma; but the fact that copper 

 has been found in leucocytes of the oyster and in other structures of inverte- 

 brates, and that there are blue and violet corpuscles, leads to the belief 

 that in certain invertebrates hemocyanin may be a component of both 

 plasma and corpuscles, and even of other structures. In all invertebrates 

 in which hemoglobin has been found it has been noted in solution in the 

 blood plasma, excepting Glycera, Capitella, Phoronis, and Solen, in which 

 it is a constituent of special blood corpuscles. 



Among the invertebrates the blood corpuscles may be colorless or 

 colored, and when the latter they may be green, red, yellow, blue, violet, 

 purple, madder, mahogany, brown, lilac, etc.; and in certain organisms 

 (Spatangus) a variety of corpuscles of different colors may be present in 

 the same blood, such as yellow, green, brown, indigo-blue, and purple. 



In addition to these exceedingly interesting peculiarities, there have 

 been noted in the bloods of different invertebrate organisms differences in 

 the specific gravity, in coagulability, and in the percentages of proteins, 

 copper, and salines; and in the kinds, sizes, composition, and relative 

 number of the corpuscles, etc. 



Gaskell (The Origin of Vertebrates, London, 1908) gives evidence and 

 arguments upon geological, anatomical, and embryological grounds that 

 load to the belief that vertebrates may have had their origin from palaeos- 

 tracans. He states (p. 65) that the evidence of geology "points directly 

 and strongly to the origin of vertebrates from the pateostraca-arthropod 



