Brain and tJie Conditions of Recovery after Compression. 3 



Adamkiewicz investigated the structures microscopically, and Dean* 

 by quantitative analysis, with special reference to oedema. 



I can find, however, no systematic investigation into the immediate 

 recovery of the brain after compression. Dean, in the course of his 

 experiments, gave attention to the recovery after the compi-ession by 

 glnss discs, but his observations were made by the unaided eje. 

 Further, the majority of his experiments, in which the brain was 

 examined several days after compression was removed, when secondary 

 changes had taken place, fall into another category than those which 

 I have carried out, for in no case were my observations prolonged for 

 more than an hour after compression, and usually the period was 

 much shorter. Moreover, contrary to the methods adopted by the 

 just named observers, the influence of the cerebro-spinal fluid in the 

 present research was excluded ; the dura mater being opened, the 

 fluid is released from all fc.nsion, and some of it escapes during the 

 procedure described below, my object being to investigate the change 

 in the brain mass alone. 



3. Description of the Apparatus for Measuring the Compression and 

 Recovery therefrom. An apparatus was designed for the purpose of 

 applying known weights vertically to the brain surface, so that tlie 

 amount of depression of the surface could be accuratsly measured, 

 and also the recoil after the removal of the weight. 



This apparatus is shown in front and back view in figs. 1 and 2. 

 It consists essentially of two supports for screwing into the skull, a 

 plunger through the medium of which to apply the weights, and a 

 dial to indicate the excursion of the plunger. 



To consider the parts in detail : the supporting pillars consist of 

 three portions, see fig. 1 (a, 6, and c). The foot (a) screws into the 

 bone, and (6) is a cap which screws on to it. The two when fitted 

 together form a socket to receive the globular end of (c) the pillar, 

 which thus acts in a ball-and-socket joint, and can be firmly fixed in 

 any position by screwing down (fc). By this means the pillar may be 

 made to assume a perpt ndicular position when the screw has to be 

 inserted into a portion of the skull which is not horizontal. 



The pillars support the dial through the medium of the slots (d, d), 

 and are fixed by screws (e, e), the slots themselves being firmly fixed 

 in position by the thumb screws (/,/). These slots allow, among 

 other movements, of lateral shifting of the dial. These arrangements 

 conveniently give great range of movement of the dial, so that the 

 plunger may be placed into a position of accurate perpendicularity. 



The plunger consists of a straight rod, carrying above a weight 

 pan (g), and, passing through the body of the dial, it has attached to 

 it by a special arrangement a thread which, looping round the axis 



* H. P. Dean, " Cerebro-spinal Pressure," ' Journal of Pathology and Bac- 

 teriology,' 1892. 



B 2 



