116 



SCIENCE. 



[N. S. Vol. III. No. 56. 



14. T. W. Mills : Cortical cerebral locali- 

 sation in certain animals. 



The paper was a report on the above sub- 

 ject confined chiefly to birds and one rodent, 

 the rabbit. The work will be extended to 

 other rodents. 



Birds : The author finds that stimulation 

 of the cortex will not produce movements 

 of the head in birds, as stated; that the effect 

 on the pupil is not constant but variable ; 

 that it is not always confined to the oppo- 

 site side, though it is usually most pro- 

 nounced on that side; that there is one in- 

 variable effect of stimulating the cortex of 

 birds, viz: drawing of the nictitating mem- 

 brane over the eye ball to a greater or less 

 extent, dependent upon the strength of the 

 stimulus. This result is not mentioned by 

 other investigators, and the author cannot 

 confirm most of Ferrier's statements regard- 

 ing the results of stimulating the cerebrum 

 of the pigeon. His own experiments were 

 made on fowls and pigeons, chiefly the 

 latter, and on both pure-bred and common 

 specimens. 



Rabbit : As regards the rabbit, the author 

 had been unable to find a cortical centre for 

 the hind leg, though such a centre is clearly 

 mapped out by Ferrier. He had no difiiculty 

 in all cases in getting cortical localization of 

 movements of the head, mouth parts, fore 

 limbs, etc., in the rabbits. He had used a 

 great variety of animals of different ages, 

 and both pure-bred and cross-bred animals. 



In the dog, cat and all the animals the 

 writer had examined, he was convinced that 

 the definiteness of the limits of centres had 

 been exaggerated and that probably new ex- 

 planations of ' motor centres ' would require 

 to be constructed. Definiteness of localiza- 

 tion is unquestionably found to increase, 

 however, as one ascends the animal scale. 



15. "W. T. Porter : A new method for the 

 study of the intracardiac pressure curve. 

 Two methods are now used to record the 



changes of pressure in the heart. In one 

 the manometer and the tube connecting it 

 with the heart are filled with liquid, to the 

 exclusion of air; in the other the distal 

 portion of the tube contains air. In the 

 former method the advantage gained by 

 employing an incompressible fluid is dimin- 

 ished by the inertia introduced by the weight 

 of the liquid column. In the latter the 

 lessening of inertia by substituting air for 

 water in a part of the tube is more than 

 offset by the loss of time unavoidable in the 

 registration of very rapid changes of pres- 

 sure by a compressible medium. The er- 

 rors inherent in these two methods explain 

 the many opposing opinions regarding the 

 form of the intracardiac pressure curve and 

 the filling and emptying of the heart. A 

 theoretically perfect method requires the 

 use of an incompressible fluid and an ab- 

 sence of inertia. In the new method of- 

 fered by Dr. Porter these conditions are 

 both fulfilled. 



A stopcock worked by an electro- magnet 

 is placed in the tube connecting the ven- 

 tricle with the manometer that is to write 

 the pressure curve. The current which 

 opens the stopcock is made by a second 

 manometer, also connected with the ven- 

 tricle, driving a wire, fastened on its 

 lever, into two mercury cups, as the 

 pressure in the ventricle rises. By ad- 

 justing the wire the circuit can be made 

 at any point in systole. If made near the 

 summit of contraction the stopcock will be 

 opened only during the maximum of ven- 

 tricular contraction, and the manometer 

 will write only the top of the intraventric- 

 ular curve, for example, the last twentieth 

 of the rise in pressure. The inertia error 

 caused by the liquid in the manometer and 

 the connecting tube passing through one- 

 twentieth its usual rise is so slight as prac- 

 tically to disappear. The true summit of 

 the intraventricular curve is thus secured, 

 free of inertia error. This summit is seen 



