May 7, 1920] 



SCIENCE 



467 



the scientist much inspiration for further 

 research and investigation. E. von Huhn 

 New York 



SPECIAL ARTICLES 



THE HEREDITY OF SUSCEPTIBILITY TO A 



TRANSPLANTABLE SARCOMA (J. W. B.) 



OF THE JAPANESE WALTZING 



MOUSE 



In 1916^ the writer in collaboration with 

 Tyzzer reported on the inheritance of sus- 

 ceptibility to a transplantable carcinoma 

 (J. W. A.) of the Japanese waltzing mouse, 

 This tumor grew in one hundred per cent, of 

 the Japanese waltzing mice inoculated and 

 in zero i)er cent, of the common non-waltzing 

 mice. When these two races were crossed, 

 the Fj generation hybrids showed sixty-one 

 out of sixty-two mice to be susceptible. In 

 these mice growth was as rapid if not more 

 so than in the Japanese waltzing mice them- 

 selves. The one exception may well have been 

 due to faulty technique for a reinoculation 

 test was not made. 



The Fj generation gave a very interesting 

 result — only three out of 183 mice grew the 

 tumor. At tliat time the results were ex- 

 plained on the basis of multiple Mendelizing 

 factors- whose number was estimated at from 

 twelve to fourteen. Simultaneous presence of 

 these factors, themselves introduced by the 

 Japanese waltzing race, was considered nec- 

 essary for progressive growth of the tumor. 

 The analogy between this case and that of 

 coat color in wild mice, dependent upon the 

 simultaneous presence of at least five known 

 Mendelizing factors was at that time pointed 

 out. 



Later^ while working with a transplantable 

 sarcoma (J. W. B.) of the Japanese waltzing 

 mouse, results were obtained which showed 

 what semed to be a somewhat simpler quanti- 

 tative condition of the same process. In this 

 case, the parent races and Fj hybrids behaved 

 as before, but the F^ hybrids gave a total of 



1 Little, C. C, and Tyzzer, E. E., 1916, Jour. 

 Med. Research, 33 : 393. 



2 Little, C. C, Science, N. S., 1914, 40, 904. 

 sTyzzer, E, E., and Little, C. C, 1916, Jour. Can- 

 cer Eeseareh, 1 : 387, 388. 



twenty-three susceptible, to sixty-six non-sus- 

 ceptible animals. It was previously estimated 

 that from five to seven factors were involved. 

 In order to determine more closely the num- 

 ber of factors, new experiments were devised 

 as follows : F^ hybrid mice themselves sus- 

 ceptible were crossed back with the non-sus- 

 ceptible parent race. This has recently given 

 a back cross generation whose susceptibility 

 would depend upon the factors introduced 

 through the gametes received from their F^ 

 parent. If one factor was involved, the ratio 

 of gametes containing it formed by the F^ 

 animal, to those lacking it would be 1 :1, if 

 two factors, 1:3; if three factors 1:7; if four 

 factors, 1 :15 ; if five factors, 1 :31 ; if six 

 factors, 1 :63 ; and if seven factors, 1 :127. 

 Susceptible and non-susceptible individuals 

 would occur in the back cross generation in 

 similar proportions. 



The actual numbers obtained were twenty 

 one susceptible to 208 non-susceptible. This 

 result may be compared with expectations on 

 three, four, five, and seven factor hypotheses, 

 as follows : 



Expected 3 factor . 



Observed 



Expected 4 factor. 

 Expected 5 factor. 

 Expected 7 factor. 



201 

 208 

 215 

 222 

 227.2 I 



Ratio 



1:7 



1:90 



1:15 



1:31 



1:127 



The observed figures fall between the three 

 and four factor hypothesis. The numbers 

 are not large enough to give a definite test, 

 but the F^ generation already mentioned is 

 interesting as a supporting line of evidence. 

 If we compare this with the expectation, we 

 find that the observed figures lie between the 



Expected 3 factor . . . 

 Expected 4 factor . . . 



Observed 



Expected 5 factor. . . 



Ratio 



1:1.3 

 1:2.1 

 1:2.8 

 1:3.2 



four and five factor hypothesis. In both 

 cases the four factor hypothesis figures are 

 close and the three and five factor hs^pothesis 



