WEIGHTS OF ORGANS IN UNDERFED YOUNG RATS 



107 



the remaining 148 (124 males, 24 females) observations upon 

 rats from the colony at The Wistar Institute in Philadelphia, 

 I am indebted to Professor Donaldson and Dr. Hatai. A care- 

 ful examination revealed no essential differences in the relations 

 of body and tail-lengths accordmg to the source of the rats, 

 so they were all combined into a single series. 



The general relations of body and tail-lengths are evident 

 from table 3 (not including the Wistar data, in which the age 

 was usually unknown). 



The average ratio of tail to body-length in table 3 was obtained 

 by calculating the ratio for each individual separately, and then 

 taking the mean of the individual ratios. The results are there- 

 by somewhat more accurate than would be obtained by simply 

 taking the ratios of the average tail and body-lengths, though 

 the difference is not great. 



TABLE 3 

 Changes in lengths of budi/ and tail 



OBSERVA- 

 TIONS 



male 



average net 

 body-weight: 



GRAMS 



male 



female 



average body- 

 length: MM. 



male 



female 



.wekage tail- 

 length: MM. 



male 



female 



average r.\tio 

 OF t.\il to 



BODY'-LENGTH 



fe- 

 male 



total 



Normal rats (full-fed) 



b. Rats under experiment (body-weight held constant) 



