94 



Scientific Proceedings (126) 



of different races than had been used in testing the other animals 

 favored the chances of a positive result. 



The following races of mice were used in the present experi- 

 ments: (1) Japanese Waltzers (Lambert strain), which origi- 

 nated from a single pair of mice isolated in 1906 and intensively 

 inbred ever since; (2) ten lines inbred three or four generations 

 from Lathrop stock by Dr. C. C. Little in his experiments with 

 X-rays; (3) Lathrop stock mice untreated with X-rays; (4) 

 Albinos of a vigorous strain inbred since 1912 by Dr. H. J. Bagg 

 of the Memorial Hospital; (5) from Dr. L. C. Dunn of the 

 Agricultural Experiment Station at Storrs, Conn., three selected 

 piebald families, inbred brother by sister for three years, descend- 

 ants of an old race originally at the Bussey Institution of Har- 

 vard University, later in the hands of Dr. J. A. Detlefson, and 

 later in the possession of a fancier; (6) Dilute Browns, a race 

 inbred by Dr. Little since 1909; (7) Storrs-Little, a race of pink- 

 eyed blacks, derived from the preceding race with the introduc- 

 tion of a single unrelated animal and subsequently crossed back 

 to the pure dilute brown for five generations; (8) Black-eyed 

 Whites, inbred brother by sister for a year by Dr. L. C. Strong 

 of St. Stephens College, mice coming from a race kept pure since 

 its introduction from England in 1913 at the Bussey Institution; 

 (9) Cold Spring Harbor wilds, comprising two sets of wild mice 

 taken at two separated places in Cold Spring Harbor, both places 

 being at some distance from the Laboratory; (10) Storrs wilds, 

 raised from wild mice collected at Storrs, Conn. ; (11) Waltzers; 

 a stock from a back cross between Japanese Waltzers and Bagg 

 Albinos made by Miss E. M. Vicari. The use of these various 

 races was made possible by the cooperative spirit of the follow- 

 ing investigators : Drs. Little, Dunn, and Strong, Mr. Gates and 

 Miss Vicari. 



Methods 



In order to secure enough serum it was necessary to kill the 

 mouse. The most successful method proved to be to etherize, 

 suspend it by its tail and cut its throat suddenly with scissors, 

 catching the blood in a centrifuge tube by means of a paraffined 

 funnel. After the blood clotted, the serum was separated in an 

 electric centrifuge and pipetted off into a small test tube. To 

 obtain samples of cells, the tip of a mouse's tail was cut off and 



