124 



Cortical Lamination and Localisation in the Brain of the 



Marmoset. 



By F. W. MoTT, M.D., F.E.S. ; E. Schuster, D.Sc. ; and W. D. Halliburton, 



M.D., F.E.S. 



(Received October 20, — Eead December 9, 1909.) 



[Plates 6 and 7.] 



The following research is one which has been carried out on lines similar 

 to that previously published by two of us* in relation to the brain of the 

 Lemur. A series of sections of the cerebral cortex has been examined in 

 order to map out the extent and boundaries of the types of cell-lamination 

 observed. It is now well known that these differences ai-e correlated with 

 differences in function, and this method of histological localisation of 

 function (as it may be termed) has been controlled by the physiological 

 method of stimulation. The histological portion of the work has been 

 carried out by two of us (M. and S.), and the physiological experiments 

 were performed at King's College, London, by the third (H.). 



Brief Introdudory Beiimrhs upon Correlation of Structure, and Function. — 

 The smooth brain of the Marmoset stands in structural development in some 

 respects midway between the smooth brain of the Lemur and the convoluted 

 brain of platyrrhine Apes higher in the zoological scale, e.g. Macacus. 

 There are certain facts in the morphology, mode of life, and liabits of these 

 three types of animals which may be correlated with tlie differences in 

 structure of their brains. The Lemur is an arboreal animal, and being 

 nocturnal and insectivorous, it depends largely upon smell as a guiding 

 sense. It is not surprising, therefore, to find large olfactory nerves and a 

 relatively large area of archi-cortex. In tlie Lemur (iialf ape) the neo- 

 cortex has not developed sufficiently to push the rhinal fissure downwards 

 to tlie under surface of the temporal lobe as is found to be the case in 

 the Ape. 



The eyes in the Marmoset are set so that the visual axes are parallel. 

 The optic nerves are well developed, and, according to Lindsay Johnston, 

 there is a macula ; it may, therefore, be assumed that this animal possesses 

 binocular vision, wliicli (nial)les it to employ this sense for obtaining food 

 hy seizing with its mouth the insects and fruits upon which it lives. 



In contrast with the Lemur, the sense of Hmcll plays a subordinato part 



* Mott and Ilallihurton, ' Hoy. Soc, E'loc.,' B, vol. 80, p. 136. See also Mott and Kelley, 

 ibid., J). 488, 1907. 



