Biological Survey — Erie-Niagara Watershed 143 



chloric acid and comparing the depth of color developed with a 

 standard whose hemoglobin content has been determined by the 

 oxygen capacity method of VanSlyke. In staging our values we 

 have placed them in the common terms in which 100 per cent 

 hemoglobin means a blood whose oxygen capacity is 18.5 cc. per 

 100 cc. of blood. Such blood was originally termed a hundred per 

 cent hemoglobin one because this was established as the average 

 among British citizens. American values seem to be somewhat 

 higher but this meaning is still quite generally used. When fish 

 blood is said to have 60 per cent hemoglobin it may roughly be 

 considered as having three-fifths the hemoglobin value of that of 

 a normal man. 



Erythrocyte counts have been made according to the standard 

 procedure using Gower's solution for dilution. Differential stains 

 for white cells have been made with Wright's stain and with the 

 strains of Giemsa and Leischman.* 



In the present report we are devoting no section to the dif- 

 ferential work upon white cells not because we question its import- 

 ance but because we have not prepared the adequate drawings 

 and microphotographs which must be included to make any such 

 discussion intelligible. At some future date we hope to present 

 material upon this important and very neglected phase of fish 

 blood. We are especially interested in developing this field in the 

 hope that it may furnish new clues in both fish diseases and 

 injuries to fish through water pollution. In regard to human 

 blood, Todd and Sanford have stated in their text, *' Clinical 

 Diagnosis", that a differential count probably '* yields more 

 helpful information than any other single procedure in blood 

 examinations". 



Before any deviations from the normal can be determined, one 

 must study the blood of a large number of sound fish from rela- 

 tively pure waters. In Table 1 we have made a preliminary 

 presentation of data upon some species collected in the Erie water- 

 shed. These data must not be accepted as standards until they 

 have been verified by many more determinations upon each 

 species. 



* To Drs. Lesch and William F. Jacobs we wish to express our appreciation for 

 stains and assistance in applying staining methods to fish blood. 



