SCIENCE.-SUPPLEMENT. 



FRIDAY, DECEMBER 11, 1885. 



PHYSIOLOGY OF THE BRAIN. 



The recently published memoir of Dr. J. Steiaer ^ 

 is an especially important contribution to this very 

 difficult field of research, and one which is likely 

 to have influence not only from its intrinsic merit 

 as an investigation, but also from the unusual 

 hterary excellence characterizing the author's pres- 

 entation of his subject. The frog was chosen for 

 the experiments on account of the comparative 

 simplicity of its brain. The experiments consisted 

 in a series of systematic removals of portions of 

 the brain ; and to the thoroughness and patience 

 with which this system of study was executed the 

 success must be attributed. Steiner removed first 

 the hemispheres, and records in his memoir the 

 observed results ; next both the hemispheres and 

 optic thalami ; then the mid-brain ; then the cere- 

 bellum ; finally the upper part of the medulla. 

 Then follow experiments with asymmetrical re- 

 movals. Together with the description of each 

 operation is given the account of the physiological 

 phenomena which ensue from it. The discussion 

 of the interpretation of the observations is kept 

 separate, — an essential advantage to the reader. 



The most important conclusion reached is, that 

 in the anterior portion of the medulla oblongata 

 there is a common centre for the co-ordinated 

 movements of the head, rump, and limbs ; or, in 

 other words, that we cannot separate the three 

 centres topographically, and can estabhsh the fact 

 of their organic connection. This central office 

 Steiner names the brain-centre (hirncentrum). By 

 ingenious experiments and reasoning he renders it 

 probable that the upper parts of the brain (bigem- 

 nia, etc.) contain no general co-ordinating motor- 

 centres, but only sensory centres and pathways ; 

 that is to say, they act to the brain-centre the role 

 of centrifugal nerves, and the brain-centre is the 

 only lomotion centre of the body. 



The relation of the brain-centre to the reflex 

 centres of the spinal cord is very remarkable, and 

 is demonstrated by the reactions of a frog deprived 

 of its hemispheres to irritations produced by vary- 

 ing strengths of sulphuric acid placed on the skin. 

 The strength is gradually increased until a reaction 

 occurs. The first reaction is a locomotion ; a little 



1 Untersuchungen uber die physiologie des froschhirns. 

 Von Dr. J. Steiner. Braunschweig. Vieweg, 1885. H°, 



stronger, and there is first a locomotion, and then 

 the well-known reflex wiping motion to remove the 

 irritant ; the wiping motion causes the stoppage of 

 the locomotion — the interpretation of this fact is 

 that the brain (locomotion) centre is more readily 

 excited than the reflex centre in the cord, and that 

 the reflex centre inhibits the action of the brain- 

 centre. This is another of the increasing number 

 of instances of the reaction consequent upon stimu- 

 lation of a given part varying with the strength of 

 the stimulus. This discovery already appears to us 

 of very far-reaching significance for the future of 

 nervous physiology. 



In a second chapter the author establishes 

 asymmetrical injury of the brain as the cause of 

 compulsory curvilinear motions {mouvements de 

 manege, rollbewegungen, clock finger movements, 

 etc.). For further details we must refer to the 

 interesting original. 



Dr. Josef Paneth brings a new contribution ^ to 

 the solution of the vexed question whether the 

 cortex cerebri of new-born animals is nritable. 

 He attributes Toltmann's negative results, which 

 are accepted in most text-books, to the use of nar- 

 cotics by that experimenter, and reports thnteen 

 experiments made by himself on dogs, of which 

 eight gave a positive, four a probably positive, 

 and one a negative result. It may be added that 

 animals which are born more advanced in devel- 

 opment (as, for instance, guinea-pigs) have been 

 already shown to have an irritable cortex at 

 birth. The only irritable area was haK a square 

 centimetre in the region of the sulcus cruciatus. 

 Microscopical examination showed the absence of 

 meduUated fibres in this region, so that Tolt- 

 mann's view that their presence is essential to 

 irritability is not sustained. Paneth's results 

 agree with those previously reached by Lemoine.- 



C. S. I\lDsOT. 



GEOLOGICAL SURVEY OF CANADA. 

 The Dominion of Canada embraces nearly half 

 the continent ; but the greater part of tliis vast 

 area is still a trackless wilderness ; and the labors 

 of the geological survey, m its earher decades, were 

 wisely concentrated upon tliose districts in the 

 eastern provinces and the valley of the St. Law- 



1 Ueber die erregbarkeit der hirnrinde neugeborener 

 hunde. Von J. Paneth. Pfliig.archiv f.physiol., xxxyW. 202. 



2 Lemoine, Contribution d la determination et d Vetude 

 experimentale des localisations fonctionelles encephaliques, 

 Paris, 1880, ' ' ' 



