318 N. W. INGALLS 



differentiated those areas which make up in large part the su- 

 perior and inferior parietal lobules and a portion of the temporal 

 lobe. These newer areas, the marked development of which is 

 so characteristic of the human cerebrum, correspond in a general 

 way with the association areas of Flechsig, the so-called silent 

 areas. A comparison of the brain of the lower Primates with 

 that of man will show that what may be referred to as the pa- 

 rietal, occipital and temporal sense areas, regions subserving 

 essentially sensory functions, make up the bulk of this part of 

 the hemisphere, while in man they are widely separated by the 

 differentiation and intercalation of newer and higher areas. Fol- 

 lowing out the comparison that has been made in describing man 

 as a ''Hirnwesen" and all lower animals as ''Darmwesen," one 

 is tempted to ascribe to these forms the possession of a mind- 

 brain and a sense-brain respectively. 



Without venturing any assertions as to the factors concerned 

 in the production of microcephaly, it may be noted that these 

 brains often present a number of pithecoid characters, depending 

 in part upon the degree of non-development. Some of these are to 

 be found in the region of the Sylvian fissure and the insula. The 

 central fissure is not so deep as the interparietal which has a ten- 

 dency to become simplified. A sulcus lunatus is common and of- 

 ten operculated. The retrocentral portion of the cerebrum has 

 suffered most on account of the great reduction in the occipital 

 and parietal regions. An examination of the drawings of the two 

 microcephalic brains described by Cunningham ('95) shov/s that 

 the parietal and occipital regions, made up of areas 5, 7, 39 and 

 40 and areas 17, 18 and 19 respectively, are very diminutive. 

 The parietal region is so small that the sulcus lunatus is well 

 forward, just behind the parieto-occipital, while the development 

 of the cortex behind, although forming a sulcus lunatus, has not 

 been sufficient, in either of these brains, to operculate that sulcus. 

 The weight of the smaller brain while fresh was 352.5 grams, 

 its relation to the body weight being 1 : 110 while in size it might 

 easily be surpassed by the brain of the anthropoids or even by 

 that of the lower apes. The main defect is in area 7 and its deriv- 



