84 FOURTH GENERAL MEETING. 



brain a human condition of the interior frontal convolution occurs, 

 it nevertheless is in such a simple condition, that it is not difficult 

 to trace its development back from such conditions as are obtaining 

 in the anthropoid apes. 



Moreover I wish to point out one circumstance which in my 

 opinion decides the question. According to Cunningham the an- 

 terior part of the second frontal sulcus should point to the frontal 

 pole, that is to say much higher than it does in man, where actually 

 its anterior part bends down to the orbital surface. Now if we 

 compare man with the anthropoid ape of equal bulk and having 

 eyes of equal dimensions, the impression from the upper roof of the 

 orbita on the absolutely much smaller frontal lobe of the ape is 

 proportionately much greater than it is in the cerebral hemisphere 

 of man, and thus the anterior end of the second frontal convolu- 

 tion ought to be pressed backwards in the ape. 



The suggestion may be put forward that the brain represented 

 by this cast was that of a microcephalic individual. This I would 

 meet by firstly referring to the overwhelming improbability of the 

 discovery of just such a pliocene idiot. Secondly I would direct 

 the attention to the calvaria which contained the brain. In the 

 region of the temporal fossae one notices a considerable lack of 

 symmetry between the two sides, the left one being much damaged, 

 and consequently the channelling seems to assume a more anterior 

 position than on the right side. The latter side should be regarded 

 as affording a true indication of the original conformation of this 

 region, a conformation closely resembling that obtaining in the ape. 

 The distance between the deepest part of the temporal fossa and 

 the upper orbital margin depends upon the relative length of the 

 maxillae, and consequently it is much greater in the ape than in 

 man. In this respect the men from Neanderthal and Spy as well 

 as the microcephalics differ entirely from the ape-type, are entirely 

 human. In Pithecanthropjis a condition obtains quite similar to 

 that in the ape, indicating a degree of development of the jaw 

 certainly not much more human-like than in the anthropoid apes. 



Viewing the predominant importance of the brain in the animal 

 kingdom and the large extent to which cerebral development 

 enables us to place vertebrates and mammals in ascending order, it 

 must be considered a prime necessity to have a reliable method of 

 estimating brain development. 



Evidently the most direct way is that of taking the volume or 

 the weight of the brain as the basis of that estimation. To a certain 

 degree this method can be applied for an estimation of the develop- 

 ment of the brain of PitJiecantliropiis erectiis, of which I was able 

 to measure exactly the capacity of the calvaria having contained 

 the chief part of the cerebrum. Duly varnished and thinly rubbed 

 with a mixture of vaseline and paraffin, the skull-cap was laid on 

 the balance, and having been equipoised, it was filled with water just 

 to a transverse plane between the frontal pole of the cerebrum and 



