Beneath this, is a deep layer occupied by large, erect and elongated pyramidal elements, 

 clearly stained, and widely separated from one another. They may be the "tassel" cells of 

 S. Ramon y Cajal. 



In the depths is a layer of well-stained, small, triangular, or fusiform cells. 



In sections stained for nerve fibres, the dense zonal layer the lamina medullaris externa of 

 other authors is the feature of greatest interest. 



Concerning the rest of this area I feel that nothing is to be gained by describing it in detail, 

 as it seems to be agreed that the whole of the lobus pyriformis subserves the olfactory function. 

 I would only mention that I have observed islets of small cells in the plexiform layer, like 

 those present in the fissura hippocampi of man, also, a layer of cells corresponding to the stratum 

 cellularuin pyramidal ium. 



The histological features of the cornu ammonis and tuberculum olfactorium may also be left 

 out of account. 



CANIS FAMILIARIS. 



In its external morphology, the brain of Canis presents many points of resemblance to that 

 of Felis ; it is therefore not surprising that numerous histological features should be repeated, and 

 that the surface maps resulting from an analysis of serial sections should exhibit a general 

 similarity. In view of this the following account will be shorn of detail and devoted chiefly to a 

 comparison of the two brains. 



CRUCIAL OR MOTOR AREA. 



The giant cells form a broad, richly-stocked, outstanding lamina, but the nested arrangement, 

 noticed in Felis and so well-marked in Homo, is less apparent. The motor cells of Canis are 

 also peculiar in being much elongated a cytological feature observed in many other parts of the same 

 animal's brain ; otherwise they present common characters, thus, numerous processes emerge from the 

 sides as well as the base of each cell, and chromophilic elements pack the body. 



In regard to numerical disposition, the postcrucial and lateral parts of the area contain cells in 

 maximum abundance, in the precrucial part there ;ire appreciably less. 



I have not attempted an accurate estimate of local variations in magnitude, a laborious under- 

 taking only to be accomplished by making and comparing a large series of outline drawings, but 

 I believe the general statement to be correct, that the largest cells occur where the number is 

 greatest, and reversely ; at the same time the difference between the smallest and the largest is 

 not very great, not nearly so pronounced as in Man. 



What was written concerning the fibre arrangement of the motor area in Felis will apply- 

 to Canis. 



Distribution (ride Plates la and 2 a). 



On the mesial surface of the hemisphere the area just appears at the upper margin, along 

 the posterior lip of the sulcus cruciatus ; and a point which a surface diagram cannot show is 

 that motor cells run along the posterior wall of the same sulcus almost to its hinder extremity. 



Viewed from the dorsal aspect the area may be again considered in relation to the sulcus 

 cruciatus, and, it may be at once stated, that it covers both walls of this sulcus, save the inner- 

 most part of the anterior bank. In reference to the latter part, I would specially point out that 

 there is no obvious indentation or fissuret to mark the particular spot on the anterior n'ssural wall 

 where the motor area ceases, but it must be noticed that the sulcus takes a bend at the point ; 

 the same obtains in the Cat, and I think comparative anatomists will agree that the flexure corre- 



