504 NAOKI SUGITA 



The "measurement L. G increases rapidly as compared with 

 the other diameters. The formula (2) which expresses the rela- 

 tion between it and the brain weight is as follows : 



L. G. (mm.) = CY X vBrain weight (grams) (2) 



grams 

 where CY will be 11.2 for a brain weighing 0.3-0.5 

 11.5 for a brain weighing 0.5-0.7 

 12.2 for a brain weighing 0.7-1.6 

 12.7 for a brain weighing 1.6-2.0 

 13.1 for a brain weighing 2.0-2.1 



The graph for the measurement L. F runs in general parallel 

 to that for L. G, as might be inferred from the relation of the 

 two diameters, but after the brain has reached the weight of 1.3 

 grams, the difference between them tends to increase owing to 

 the slightly more rapid growth of L. G. The difference between 

 L. F and L. G ranges between 0.20 and 1.35 mm. In general, 

 the difference tends to decrease from birth (0.78 mm.) to the 

 brain weighing 1.0 to 1.1 grams, at which stage the difference is 

 least (0.20 to 0.26 mm.), and then increases again (up to 1.35 

 mm.) as the brain weight advances. 



At birth the width {W. B and W. D) surpasses considerably the 

 length (L. G and L. F) and the cerebrum is short and rounded. 

 But very soon the length begins to increase more rapidly than 

 the width and the shape becomes more and more elongated. 

 The measurement L. G surpasses W. B and the measurement 

 L. F surpasses W. D at the stage when the brain reaches 1.6 

 grams in weight. 



The width-length index of the brain, here used, is obtained by 



the formula — '- It is at birth about 127, reaches ICO 



L.F 



in a brain weighing 1.3 — 1.5 grams and is about 95 in old age. 



The height of a brain may be obtained by the following for- 

 mula (3) : 



Ht. (mm.) = Ch X V Brain weight (grams) (3) 



grams 



where Ch will be 8.6 for a brain weighing 0.3-1.2 

 8.3 for a brain weighing 1.2-1.6 

 7.9 for a brain weighing 1.6-2.1 



