1878.J 



Mr. Lockyer. Spectrum Analysis. 



49 



this feature still predominates in other portions of the motor area 

 where the size of the cells no longer warrants ns in calling them giant 

 cells, their position in the order of lamination, their general form and 

 distribution in clusters sufficing to identify them as the same elements. 



This disparity in size between these elements in the fourth layer of 

 the motor area induces us to reject the term giant cell as applied 

 generally to this formation, and to call them in preference the gan- 

 glionic cells of the cortex. Their close resemblance to the ganglionic 

 cells of the spinal cord has been fully recognised by Betz and other 

 observers. 



EXPLANATION OF DRAWING'S. 



Plate 1. A section taken through the ascending frontal at its upper extremity, ex- 

 hibiting the five layers of the cortex as seen magnified 87 diameters. 



Plate 2. The ganglionic cells of the fourth layer of the cortex from an area opposite 

 the first frontal on the ascending frontal convolution. In the lower group 

 the various forms assumed by these giant cells are well shown, whilst the 

 upper group represents the appearance presented by sections carried across 

 their long axis. The latter method illustrates the wide area commanded 

 by their outspreading branches. 



Plate 3. A scheme illustrative of the exact number and arrangement of the ganglionic 

 cells at different points of the ascending frontal and two upper frontal gyri. 



Each curved line is supposed to represent the boundary line of a section 

 carried vertically through the ascending frontal from before backwards. 

 The right hand portion of the curve, therefore, represents the side adjacent 

 to the ascending parietal ; the left hand segment of the curves represents 

 the frontal aspect, from which the frontal gyri arise. Eigs. 1 and 2 

 serve to localise the site of these sections. The exact number of these 

 cells, and their relative positions, were first sketched, as accurately as 

 possible, under a quarter-inch power, and the sketch reduced by photo- 

 graphy. That portion of the scheme relating to the two frontals shows, 

 at R, a section through the area of the first frontal carried across its length, 

 and at S in like manner, a section through the ascending frontal opposite 

 the second frontal, and, therefore, carried along the length of that convolu- 

 tion. 



N.B. — Plates 1 and 2 represent sections obtained from frozen brain, by 

 means of the ether microtome. 



III. " Researches in Spectrum Analysis in connection with the 

 Spectrum of the Sun." By J. Norman LOCKYER, F.R.S. 

 Received November 17, 1877. 



(Abstract.) 



The author refers to the work already done in the new map of the 

 Solar Spectrum as enabling the chemical constitution of the Sun's 

 atmosphere to be studied under more favourable conditions. 



YOL. XXTII. E 



