1911.] the Transmission of Acquired Characters. 



557 



recognisable entity, and the second is Brown-Sequard's statement that,, 

 although he had had many thousands of guinea-pigs under observation, he 

 had never observed the condition save in those especially operated upon 

 (11, 25). 



Apart from the phenomenon itself, two other consequences of a section of 

 the great sciatic nerve are of interest. In the first place, the special area of 



Fig. 1. — February 14, 1910. Becord of a "complete" Brown-Sequard reaction in a 

 guinea-pig. The mechanical stimulus was applied to the right side of the neck 

 between the points X and Y of the signal line (ordinates x, jS : y, y'). Between 

 these points the scratch was confined to the right hind limb, and had this been the 

 only reaction the phenomenon would have been "incomplete." But it will be 

 observed that, on cessation of stimulation at Y, scratching movements appear in the 

 left hind limb, then cease and reappear in the right hind limb— thus producing a 

 " complete " reaction. The record indicates flexion as a rise and extension as a fall 

 of the curve. The rapid up-and-down movements indicate the "beats" of the- 

 scratch. 



skin usually becomes infested with lice (6, 7, 12) ; and in the second place 

 the animals often acquire the habit of nibbling the anaesthetic parts of the 

 foot. 



In 1860 (8) Brown-Sequard stated that this peculiar phenomenon might 

 appear in the offspring of affected guinea-pigs. The paper is simply a note,, 

 in which he declares that he had seen the transmission in six cases, and that 

 the primary injury was to the spinal cord. This statement was accepted by 



