HARVEY M. SMITH. 



Red blood cells were measured by means of a scale which was 

 so constructed that each division on the scale corresponds to one 

 micron in the oil immersion field (B. <X: L. 1.9 mm. obj.) with lox 

 ocular and 160 mm. tube length, when the scale is placed on the 

 table beside the microscope and viewed through a camera lucida 

 with mirror set at an angle of 45 and the arm length set at 103 

 mm. With the aid of this scale the dimensions of red blood 

 cells were measured, 50 cells being measured from each slide, and 

 from one to five slides being used for each animal studied. From 

 the average length and width thus obtained the surface of the 

 average corpuscle for each animal was computed, assuming no 

 thickness, from the formula irLW/2 where L is the maximum and 

 W the minimum diameter. This formula follows from the for- 

 mula for a regular ellipse, -jrab, where a and b are the long and 

 short radii. The surface is used as the significant figure rather 

 than the length and width because all corpuscles are not the 

 same shape, length and width have different ratios, and therefore 

 the dimensions do not give a direct index of size. 



III. RESULTS FOR THE DIFFERENT SPECIES OF AMPHIBIA. 



Table I. gives the results for the various species used. Where 

 a space is left blank, no data were obtained on the particular 

 point concerned. For instance it will be noticed that sex is not 

 given in a number of cases, and in the same cases usually no 

 blood cell measurements are given. In these cases the animal 

 died and it was not considered safe to make blood cell measure- 

 ments on such animals in which post mortem changes had had 

 time to occur. Therefore they were not autopsied at all, and 

 thus no data were obtained on sex. In several species it was 

 impossible to obtain samples for carbon dioxide determinations, 

 although one or several had already been used for blood smears. 



A short description of the material and results for each species is 

 given below. The species are taken in the same order as in the 

 table; that of red blood cell sixe. 



Amphiuma means (Gordon). This species has the largest 

 corpuscles known for any amphibian. Three adult specimens 

 and one young were obtained from New Orleans. Measure- 

 ments of carbon dioxide output were made at intervals over a 

 period of two weeks. The animals showed evidence by their 



