846 THE SPINAL CORD. 



mechanical injury of some part of the nervous system, and is of tem- 

 porary nature, may be conveniently included under " shock." By Goltz it 

 is considered as entirely a collection of inhibition phenomena. But it 

 has its analogue, no doubt, in the " block " (Romanes, Gaskell) in a con- 

 ducting tissue (medusa subumbrella, heart) ensuing on mechanical 

 interference. Whether such phenomena are best included under the 

 head of inhibitions is very questionable. 



Among laboratory animals it is in the monkey that on the whole 

 " spinal shock " appears at maximum. As studied in that animal, whether 

 the site of spinal transection lies near the front or hind end of the 

 thoracic region, appears to make slight difference to the general 

 result, apart from determining the mere number of spinal segments 

 displaying the phenomenon. The " shock " appears to take effect in the 

 aboral direction only. 1 



Section below the brachial enlargement little if at all disturbs the reactions 

 of the upper limb, although the number of headward running channels of con- 

 duction ruptured by such a section is enormous. Striking instances of the 

 absence of headward spread of the depression due to " shock " are afforded by 

 transections abutting on the lower edge of the fifth cervical segment ; these 

 depress the respiratory activity of the phrenic motor cells hardly at all, even 

 momentarily. On the aboral side of the transection, depression is profound. 

 Analogously, the sudden cutting off of all that stream of centripetal impulses 

 continually pouring for conscious and subconscious elaboration into the 

 encephalon from the cutaneous, articular, and muscular sense organs of the 

 tail, limbs, trunk, and neck, and from the viscera, does not seem at all to 

 disturb the reactions of the head and brain. The animal immediately after 

 the section will contentedly direct its gaze to sights seen through the window, or, 

 if the section have been below the brachial region, may amuse itself by catching 

 flies on the pane. Similarly, the head half of the worm Thysanozoon 2 or 

 Allolophobus 3 is said to continue the movements of progression almost undis- 

 turbed by quick transection across its middle. The bee, if while it is sucking 

 honey the abdomen is suddenly cut off, will rear itself for^ a moment and 

 then quietly continue sucking. 4 The exclusively aboral direction taken by 

 shock seems universal in the nervous system. In the monkey, when the tran- 

 section has been quite far forwards, e.g. at the first cervical level, there seems 

 a tendency to drop off rapidly to sleep ; but it is very doubtful whether that is 

 due to any depression of the nervous organs in front of the section, other 

 than that depression of function one might expect from the coincident fall 

 of the arterial blood pressure and body temperature. In the cat a high tran- 

 section, e.g. brachial or cervical, seems to frequently induce in front of the 

 lesion not a depression but an exaltation of function, the region of the 

 trigeminal distribution appearing hypersesthetic. 5 The reactions from the 

 head organs in Astacus 6 seem exalted by section of the nerve cord in front 

 of the thoracic ganglia. 



After high cervical transection, " shock " appears more severe in 

 the fore-limbs than in the hind. For an hour or so it may be 

 difficult to elicit any reflex movement from skin innervated behind 

 the transection, whether by mechanical, thermal, or electrical stimuli. 

 An apparently crossed reflex is, at least in my experience, among 

 the earliest obtainable, namely, the crossed adductor reflex and the 



1 Sherrington, Phil. Trans., London, 1897. 



2 J. Loeb, Arch.f. d. ges. PhysioL, Bonn, 1894, Bd. Ivi. 



3 W. W. Norman, ibid., 1897, Bd. Ixvii. 4 A. Bethe, ibid., Bd. Ixviii. 



5 Sherrington, Phil. Trans., London, 1897. 



6 Bethe, Arch.f. d. ges. PhysioL, Bonn, 1897, Bd. Ixviii. 



