262 Castle. 



niodilViiig- cliararters which Mendelize, Dr. and Mrs. HAGEnooRN now 

 pulilish tlieir complete data. They say (page 16n): 



"The records, however complete, were far from givino- ns a clear 

 oversight over the results so far obtained. When, however, Prof. Castle 

 published his paper in the American Breeders Magazine, and thus 

 showed still to adhere to the belief, that he had, by selection, modified 

 a gene (or in his own words a unit-character) we thought it worth while 

 to put the pictures of our rats together, and arrange them in i)edigrees, 

 to show clearly what selection had accomplished in the few generations 

 we had bred.'" 



Now what do these pictured records "sliovv clearly""? The reader 

 may refer to Fig. 3 and see for himself. They show first, that the 

 "some few hundreds" of Dr. Hagedoorns 1911 paper have dwindled 

 down to 5i) offspring (omitting four all)inos) distrilnited) in tlic '"few 

 generations" mentioned, as follows'): 



Generation Numlier of matiiiffs Numbei' of offspring Remarks 



11 Unselected 



7 



26 First selection. 



9 Selected son bred 



to mother. 

 Po 1/2 1 6 Second selection. 



Two full selections were made, the latti^r, however proilucing oui\' 

 a single littei- of (i young. This seems I'ather a slender basis for 

 generalization on the effects of continued selection. So far as the re- 

 cords show anything, they supjtort what I have stated on various occasions, 

 that the darker individuals of a litter produce darker offspring and 

 vice versa. 



Regarding tlie Pi generation the authors say "The variation in 

 this family is discontinuous." But on referring to the pictures one may 

 well inquin^ at what point the discontinuity comes in. Is it at 126, 

 53, 52, 51, 01' 48? There is no ai)i)arent break in tiie seiies of pictures 

 as arranged in ordei' of increasing Idackness. Is tlieie "non-genetic" 

 blackness here wliirli obscures tiie supposed discontinuity? If so, what 



') I leave out of consiileratiou here the three matings shown in P'ig. 4, which 

 involve in every case tlie "Irisli" pattern and accordingly have nothing to do with the 

 straight selection series. 



