94 SHINKISHI HATAI 



making cross references to the data on a series of inbred albino 

 rats which have been grown here by Dr. King for several years 

 past. There are already on hand data for over 800 inbred rats 

 of various body weights — mostly very large. In addition to 

 these, the records for several hundred Norway and hybrid rats 

 were also employed for cross reference. Therefore, although 

 our data on the stock albino rats are not very extensive, never- 

 theless, by the aid of the various cross references, it has been 

 possible to produce graphs which are believed by the present 

 writer to be nearly correct in their essential features. 



In table 1 the calculated weights of the organs for various values 

 of the body weight are given. This table has been used in making 

 the charts and for the purpose of graphic interpolation. Com- 

 plete tables giving the calculated weights of all the individual 

 organs for every millimeter of the body length will be published 

 later for the purpose of laboratory reference. Table 2 gives the 

 mean values of the observed weights for all the organs examined. 



We now pass to a brief description of the formulas, the graphs 

 based on them and the relations between the observed and com- 

 puted values. 



In charts 1 to 12 the growth of organs in weight for increasing 

 body weight is illustrated. Since I have not taken the age into 

 consideration, any given body weight may be represented by 

 individuals of various ages. In general, the weight of the organs 

 follows closely the body weight, and therefore in rats growing 

 normally, the weight of the organs may be considered as a func- 

 tion of the body weight. We notice in all cases that the greater 

 fluctuations occur among the larger individuals. This is due, 

 in part at least, to the fact that the relation between body weight 

 and body length varies much more in the larger than in the smaller 

 animals, owing either to abnormal fat deposition or emaciation. 

 Such fluctuations may be reduced to a minimum by computing 

 the normal body weight from the observed body length (Donald- 

 son '09) and substituting the computed value of the body weight. 

 However, I have not adopted this method except in the case of 

 a few observations where the emaciation was very considerable. 



