SCIENCE. 
25 
SATURDAY, JULY 17. 1880. 
A REMARKABLE PECULIARITY OF AN AN- 
THROPOID BRAIN. 
BY E. C. SPITZKA, M. D. 
Among the features of the cerebral surface, on 
whose presence or absence the differential characters 
of the human brain as compared with that of the an- 
thropoid apes, have been established by anatomists, 
the so-called transition convolutions occupy a promi- 
nent place. As is well known, the occipital and pa- 
rietal lobes of the human brain are connected with 
each other by means of short gyri, which bridge over 
those fissures, which if uninterrupted would separate 
these lobes like a chasm. First described by Gratio- 
let as plis de passage , and known among English 
writers as annectant or transition gyri ; it is the one 
among them which borders on the great longitudinal 
fissure that has been most closely studied. 
With exceptions to be noted, writers on the human 
and anthropoid brain agree in stating that the brain 
of the Chimpanzee differs from the human brain, in 
failing to exhibit this, the so-called first transition con- 
volution, inasmuch as it is always concealed by the 
junction of the internal with the external perpendicu- 
lar occipital fissures. 
The same authorities also observe that while there 
is this sharp demarcation between the brain of the 
Chimpanzee and that of man, that another anthropoid 
resembles the human being in this very respect, namely 
the Orang, in which animal this fissure is present and 
superficial. 
The decease of a large number of anthropoid apes 
which have been on exhibition at various times during 
the past few years at the New York Aquarium, and 
whose bodies were kindly placed at my disposal by 
the managers of that institution, has enabled me to 
extend the observations made on the brains of the 
Chimpanzee and Orang by previous writers. 
The first Chimpanzee’s brain obtained by myself, 
differed in no noteworthy respect from those described 
by Marshall, Gratiolet, Pansch and others, and was 
utilized for microscopical study.* The second, that 
of a very large animal, one which had reached the age 
of puberty, and weighing 389.86 grammes, presented 
the interesting anomaly I am about to describe, and 
whose demonstrable existence adds another proof to 
the many which have been accumulating, that there is 
no absolute and impassable line of demarcation be- 
tween the human and simian brain. In the first place, 
as shown in the subjoined outline diagram, the occipi- 
tal lobes of this brain are unsymmetrical. 
On the right side the internal perpendicular occipital 
fissure does not coalesce with the external, while on 
the leftside it does. The result is that on the right side, 
we have an excellently developed first transition gyrus 
[G, G ] evident and superficial, as in the human being, 
while on the left side it is concealed as in the ordinary 
Chimpanzee type. That is, the right side of the brain 
*The peduncular tracts of the anthropoid apes. Journal of Ner- 
vous and Mental Diseases , July, 1879. 
Outline diagram of o:cipital end of cerebrum, dorsal view, x%. 
shows a higher grade of development than the left. 
In so far as the left side is usually the better developed 
one this asymmetry is anomalous. Yet it shows that 
the old line of demarcation is not a correct one. 
Though the transition gyrus is concealed on the left 
side, yet a portion of it is visible, showing that on the 
whole this brain exhibits a tendency to a more human- 
like relation. 
If we now proceed to compare the transition gyri 
of an Orang’s brain with those of this Chimpanzee’s 
right hemisphere, and of Man, we are struck by the 
observation that its disposition and proportions are 
more human-like in the Chimpanzee than in the 
Orang. And this applies to the Orang in my posses- 
sion as well as to those figured by Tiedemann, Gra- 
tiolet and Bischoff. Taking the occipital lobe of the 
Orang as a whole, its physiognomy, if I may so term 
it, is lower and less human like, than that of the Chim- 
panzee. 
The fact that the arrangement of the gyri and fis- 
sures bordering on the occipital fissures is thus shown 
to be inconstant, and that as Vogt has humorously 
shown, some of the South American monkeys resem- 
ble the human being more strongly in this respect 
than the average Chimpanzee and Gorilla (Pansch), 
should make us careful in basing fundamental charac- 
terization on such slight morphological factors. 
I should state that Marshall and Bischoff while fail- 
ing to ever find the gyrus under consideration appear- 
ing at the surface, yet have identified it as concealed 
in the depths of the perpendicular fissure. 
In the occipital lobe of an imbecile recently 
executed for murder at St. Louis, and whose brain 
was referred to me for examination, I have found the 
external occipital fissure perfect as in the embryo, 
though intersected by collateral fisssures, and exhibit- 
ing a bevel, repeating to some extent its disposition 
in the anthropoid apes. 
The Albert Medal of the Society of Arts for 1879, 
was presented to Sir W. Thomson lor his electrical re- 
searches, especially those relating to the transmission of 
telegraphic messages over ocean cables, last week, at a 
meeting of the council, held at Marlborough House. At 
the same time the Albert Medal for the current year was 
presented to James Prescott Joule, F. R. S., for the re- 
searches by which he established the true relation be- 
tween heat, electricity, and mechanical work. The con- 
versazione of the Society was also held last week, when 
Mr. Donald Currie, M.P., was presented with the Fother- 
gill Gold Medal, the award of which we recently an- 
nounced. 
