STUDIES ON CYTOLYSINS 



77 



tween the precipitin and the cytolysin reactions of the blood, it 

 was felt that if the lens had so sensitized the fowls that precipi- 

 tins were formed, one might infer that cytolysins had also been 

 generated. 



When ready to make these precipitin tests, several other 

 species of Peromyscus were available from the experimenter's 

 own and from Dr. Sumner's collections, hence it was possible to 

 make a series of comparative tests. These are set down in full 

 in table 4 because of the rather interesting relationships indi- 

 cated. Since the tests were merely incidental to the other 

 work, they are to be looked upon as suggestive rather than as 



TABLE 3 



finished experiments. Judging from the results of these few tests, 

 which are in harmony with the well-known work done several 

 years ago by Nuttall,^ it might be well worth some one's time to 

 choose a genus such as Peromyscus and make extensive and ac- 

 curate precipitin tests of various kinds on the different species 

 with the view of finding physiological relationships and deter- 

 mining how these correspond to present taxonomic grouping and 

 to geographical distribution. Interesting disclosures regarding 

 conditions in hybrids should also come to light. For such work 

 one should have narrow, very carefully graduated centrifugal 

 tubes by which the amounts of precipitation could be accurately 

 measured. 



1 Blood immunity and blood relationship, Cambridge University Press. 



