ALBINO EAT VISCERA, GLANDS, EYEBALLS: WEIGHTS 93 



between 5 and 50 grams in body weight. I have however, tested 

 with my own Umited data the weights of the organs belonging 

 to the rats of these body weights (5 to 50 grams) and found that 

 the two sets of data agree perfectly. 



In fact, in this period all the organs determined by both of 

 us agree closely, though I have not used the data obtained by 

 Dr. Jackson, except in the cases named. Thus in the cases of 

 the three organs mentioned above, the observed data are those 

 furnished by Dr. Jackson and none of my own have been addad, 

 while after 50 grams in body weight, all the data are from my 

 own observations made on the rats from the colony at The 

 Wistar Institute. In the case of all of the other organs, the 

 formulas are based on my own data alone. 



The total number of The Wistar Institute rats examined by 

 me for the presfent purpose was 271 (220 males and 51 females) 

 while Dr. Jackson examined 344 (165 males and 179 females) 

 at the University of Missouri. The actual number of rats used 

 in the case of each organ will be stated when the formula is 

 presented. 



It should be added that when a rat with infected lungs was 

 found — the rest of the organs except the alimentary tract being 

 apparently nomial — the records for the lungs and alimentary 

 tract were discarded, while the dat^ on the remaining organs 

 were emplo^^ed. Furthermore, in order to simplify the matter, 

 the determinations of the constants were based on the male data 

 alone, as in the case of most of the viscera, there is no clear evi- 

 dence of a sex difference. 



When however the sex differences are evident, the constants 

 were determined separately for each sex. As will be seen later, 

 there are no distinct differences between the two sexes, except 

 in the case of some of the ductless glands. The formula deduced 

 for the males can therefore also be used for the females unless 

 the contrary is explicitly stated. 



It should be noted also that in determining the form of the 

 graphs, especially at the upper end where both my data and 

 those of Dr. Jackson were scanty, I have been much helped by 



