354- 'Journal of Comparative Neurology and Psychology. 



as "dwarfs." In addition also, we have records on rats experi- 

 mentally stunted (Hatai '04, '07B and '08). 



In the accompanying table 3, there is given a summary of the 

 observed and calculated weights of the brain and spinal cord in 

 these three groups. The calculations are based on the weight of 

 the body at the time of killing, and were made by the use of form- 

 ula [i] for the brain, and formula [3] for the spinal cord. The 

 individual records used in forming this table 3 do not appear in 

 the general table. 



TABLE 3. 

 Data on special groups; condensed statement; all the measurements are averages. 



On looking at the columns giving the observed brain weights, 

 and comparing these with those calculated, it appears that in the 

 case of the "giants" there is a difference of .027 gm., or 1.5 per 

 cent, in favor of the calculated weight. In the case of the "dwarfs," 

 a difference of .033 gm., or 2.5 per cent, in favor of the calculated 

 weight, and in the case of the rats experimentally stunted, a dif- 

 ference of .002 gm., or 0.1 per cent, in favor of the observed 

 weight. Within the same range of body weights (47.2 to 179.8 

 gms.), as shown in table i and chart 3, the calculated values are 

 on the average 1.6 per cent above the general observed means, 

 so that the special groups in question show on the whole no 

 greater deviation than that found in the larger series. From this 

 it follows that the relations of the brain weight to the body weight 

 are not modified by either excessive or deficient growth under the 



