[MILLS] FUNCTIONAL DEVELOPMENT OF CEREBRAL CORTEX IS 



feature contrasting in the rabbit very strongly witli the condilion in the 

 dog and the cat. 



These movements in the rabbit occur at a date almost, if not quite, 

 as eai'ly as those of the fore-limbs. 



Equally noteworthy is the fact that in very young rabbits in which 

 the movements referred to above occur, movements for the hind-limbs 

 cannot be induced under similar circumstances. 



The cavy contrasts strongly with the rodents mentioned above, as 

 well as with the dog and the cat, by the fact that there is good cortical 

 localization at or within a few hours after birth. 



Examination of the Work of Others, etc. 



When my own investigation was well advanced, and I had obtained 

 results unbiassed by the conclusion of others, I undertook a careful exam- 

 ination of the important research of Soltmann/ wliich is about the oldest 

 and best on this subject. 



This investigator experimented on dogs and rabbits. He tried 

 chloroform and ether as anaesthetics, but abandoned them for subcutane- 

 ous injections of morphia. As he points out, the fir.st two, ascompai'ed 

 with the latter, are open to the objection of favouring haemorrhage. 

 • Morphia, however, seems to me to be very vinsatisfactory, as it is difficult 

 to produce by it the exact degree of narcosis required, and in all experi- 

 ments of this kind it is important to be able to vary the depth of the 

 narcosis. With a certain degree of narcosis it is impossible, as has been 

 the experience of many workers on the brain, to get a reaction with any 

 strength of current. There is a definite degree of ana\sthesia which is 

 essential to enable one to draw correct conclusions. I place no reliance 

 on results obtained without anaesthesia, and experience enables one to 

 determine when reactions are reliable. 1 have in all cases used ether, 

 because by it the depth of the narcosis can be rapidly and nicely varied — 

 a most important matter, as before stated, when one has to deal with the 

 brain of a very young animal, so readily is it exhausted or in some 

 way injured. As previously indicated, many experiments have been re- 

 jected as unreliable from haemorrhage, etc. Nevertheless my results in a 

 large degree are in accord with those of Soltmann, as 1 shall now pro- 

 ceed to show. He found that in dogs the cortex was not excitable in the 

 "newlj'-born," but that the fibres of the internal capsule were; that the 

 fore-limb was the first to respond to electrical excitation of the cortex, 

 then the hind-limb, and later the face, if it be true that morjjhia 

 heightens the excitability of the white fibres, as some affirm."'' this may 

 exi^lain the greater readiness of Soltmann to claim a much earlier activity 



1 Jahr. f. Kinderheilkunde u. Phy.s., Erziehung, 1876. 



2 Bubiiofftind Heidenhaiii, Piluger".s Archiv. f. Physiologie, 1881. 



