76 



Scientific P oceedings (80). 



which may affect the interpretation of the results. And the pro- 

 cedure itself is supposed to produce shock through its great trauma 

 or not to produce shock, according to the demands of the hypo- 

 thesis which is to be sustained. Sherrington's 1 statement that 

 trauma qua trauma has little or nothing to do with the onset of 

 shock is frequently overlooked. 



The various reflex mechanisms associated with the eye have 

 been investigated largely in decerebrated animals. Mayo 2 de- 

 cerebrated a pigeon leaving the optic tubercles and the crura cere- 

 bri, and then cut below the medulla oblongata. The optic and 

 the third nerves were left intact within the cranium. On pinching 

 the central end of the stump of the optic nerve of one side, the iris 

 contracted. Mayo states that contraction of the pupil could be 

 obtained immediately after decapitation — a violent surgical pro- 

 cedure. The conjunctival reflex in the rabbit seems to involve 

 the myelencephalon as well as the meteneephalon. 3 It persists 

 unaffected by shock, when transection is made in front of the pons. 



The slow deviation of the eyes in response to stimulation of the 

 otic labyrinth persists after decerebration and after splitting the 

 entire meteneephalon in the mid line, but the quick component of 

 nystagmus — the quick jerk of the eyes back to the mid line or to 

 the line of vision — is abolished. Removal of one cerebral hemi- 

 sphere abolishes the quick movement when the slow movement 

 of the eyes is directed to that side, but does not affect the quick 

 movement when the slow movement of the eyes is directed to the 

 side of the remaining cerebral hemisphere. 



In view of the facts that (i) decerebration does not affect the 

 magnitude of the slow movement of the eyes in response to laby- 

 rinthine stimulation, (2) removal of one cerebral hemisphere affects 

 the quick movement of the eyes in one direction only, (3) that the 

 quick movement of the eyes is abolished when only the temporal 

 and basal portion of the cerebral hemisphere of one side is re- 



1 Sherrington, "Integrative Action of the Nervous System," New York, 1906, 

 pp. 241-243. 



2 Herbert Mayo, "Anatomical and Physiological Commentaries," London, 1823, 

 Vol. II, pp. 4, 18, 136; cited by Sherrington, Schafer's "Text Book of Physiology," 

 1900, Vol. II, p. 812. 



3 Exner, Archiv fitr die gesammte Physiologic 1874, VIII, p. 530; Schafer's Text 

 Book of Physiology, 1900, II, p. 892. 



