74 



ANATOMY 



Sahli instrument (Newcomer's model) was also used. The dif- 

 ferential count was made with Wright's blood stain and the 

 percentage values based on 500 leucocytes. In making smear 

 preparations the drop was gently spread over the slide with a 

 cigarette paper instead of using another slide for this purpose. 



The foregoing determinations by Rivas, Nowrey and Margot 

 have all been given because they were made several years apart, 

 were all on rats from The Wistar Institute Colony, and all on 

 blood from the tail. 



During the interval from 1914 to 1921 the colony was in a 

 good nutritional state, though tending to improve in this respect 

 towards the end of the period. The relation of most interest, 



TABLE 41 



Average number of leucocytes and percentages of polymorphonuclear cells and small 



lymphocytes 



here brought out, is that between the P.M.N. and the S.L. 

 groups. These data are summarized in table 41. 



As table 41 shows, the relations of these two groups are sim- 

 ilar in the three series and may therefore be regarded as apply- 

 ing to fertile and well grown albino rats in the Wistar colony. 

 This point is noted because quite different values are reported 

 for the normal albino rats from other laboratories. 



Thus Kleineberger and Carl '12, Eyre '13, Cramer, Drew and 

 Mottram '21 and Cramer (personal communication, '22) all 

 give in normal albino rats percentage values for the small lympho- 

 cytes which are about twice those for the polymorphonuclear 

 cells, while the records from The Institute up to 1921 show 

 consistently a reverse relation. No explanation for this strik- 

 ing contradiction has yet been found, but as our data are from 

 the same strain as was used for the other tables here given, 

 these are the values presented. 



