Donaldson, Brain and Spinal Cord of Rat. 157 



Second. — The individual records have been tabulated and are on 

 file at the Institute. They are therefore available for use by other 

 investigators, and may be had by application to the Director of 

 The Wistar Institute. 



Third. — It is hoped that this condition will be only temporary, 

 and that when this group of investigations is completed, the entire 

 series of individual records employed for them can be printed in 

 the form of tables in a special brochure, thus making them generally 

 available. At this time only the mean values of the observation are 

 tabulated. 



We turn at once, therefore, to the consideration of the special 

 questions : — 



1. The body length of the albino rat according to body weight. 



On Chart I, so far as is possible without confusion, the individual 

 records for body length (170 males and 148 females) are entered 

 according to the body weight. The continuous line on the chart 

 shows the theoretical curve. As can be seen, the distribution of 

 the records is such as to fit a theoretical curve that rises with dimin- 

 ishing rapidity, and so far as it can be plotted, is still bending 

 towards the horizontal. A distinction between the sexes in the rela- 

 tion of body length to body weight, though present, is hardly to be 

 seen on Chart I. The mean values for the body lengths are given in 

 Table 2. Making use of these data, the weight length ratios have 

 been determined for the series in hand. 



Table 1 gives the numerical expression of the relations obtained 

 by dividing the calculated body length (for both sexes combined, 

 see Table 2 ) by the body weight. 



The ratios thus obtained are given in Table 1, and these show 

 that the albino rat becomes relatively shorter as its weight in- 

 creases. 



By means of a correlation table based on groups differing by 

 10 grams in body weight and 10 mm. in body length, the mean 

 statures for given body weights have been calculated. This has 

 been done for each sex separately, as well as for both sexes taken 

 together, and the final values obtained are given in Table 2. 



When the means for the males are compared with those for the 



