184 BRAIN-WEIGHT AND SIZE IN RELATION 



it would seem, to be in no degree illogical to look for the accom- 

 paniment of the inversion of the process by an approximation, in 

 some instances, to certaia capacities and functions of the ape. But 

 there are no indications of this. In some examples of microcephaly, 

 the so-called animal propensities do indeed manifest themselves to 

 excess; but there is no reproduction of the animal nature, instincts, 

 or capacities, analogous to the scale of cerebral development of the 

 orang or chimpanzee. A microcephalous idiot, who died at the age 

 of twenty-two, in St. Bartholomew's Hospital, London, had a brain 

 weighing only 13-125 oz., or 372 grammes. In describing this case, 

 Professor Owen remarks : *' Here nature may be said to have per- 

 formed for us the experiment of arresting the development of the 

 brain almost exactly at the size which it attains in the chimpanzee, 

 and where the intellectual faculties were scarcely more developed. 

 Yet no anatomist would hesitate in at once referring the cranium ta 

 the human species." And so is it with the encephalon. The brain, 

 of the chimpanzee is a healthy, well-developed organ, adequate to 

 the amplest reqturements of the animal; whereas the microcephalous 

 human brain is inadequate for any efficient, continuous cerebral 

 activity : not merely limited in its range of powers. Much, how- 

 ever, may yet be learned from a careful attention to the imperfect 

 manifestations of activity in certain directions, in cases of microce- 

 phalic idiocy, and noting the predominant tendency in each case, 

 with a view to subsequent examination of the brain. By this meana 

 it may be found possible to refer certain forms of mental activity to 

 special variations in the structure of the organ, or to distinct mem- 

 bers of the encephalon. 



Dr. Laennec recently exhibited to the Anthropological Society of 

 Paris a microcephalous idiot of the male sex, aged fourteen years. 

 " This child is entirely unconscious of his own actions, and his intel- 

 lectual operations are very few in number, and very rudimentary. 

 His language . consists of two syllables, oui and la, and he takes an 

 evident pleasure in pronouncing them. He takes no heed in what 

 direction he walks. He would step off a precipice, or into a fire." 

 Attention was specially directed to the idiot's hands : "The thumbs 

 are atrophied, and cannot be opposed to the other fingers. The 

 palms of the hands have the transverse creases, but not the diagonal 

 — the result of the atrophy of the thumbs. Hence the hand resembles 

 that of the chimpanzee. The dentition too is defective. Though 



