G. NATURAL HISTORY AND ZOOLOGY. 295 



Large as materially to affect the number of salable fish pro- 

 duced, as they sooner or later succumb in the struggle for 

 existence. 



Dr. Knoch, of Moscow, has lately been studying the nature 

 of malformations in the trout, salmon, and whitefish, and 

 finds the most common monstrosities to consist in the pos- 

 session, first, of two heads; second, of a double vertebral 

 column and cord ; third, of malformation as regards diver- 

 gence of the body from its axis of length ; fourth, of defects 

 of the organs of locomotion ; fifth, of anomalies in the vege- 

 tative sphere; sixth, of defects in the organs of sense. 



It is possible that similar malformations occur in equal 

 proportions in other fishes, but such of these as come under 

 the cognizance of the student are usuallv so small as not to 

 be appreciable. Malformations are, indeed, quite common in 

 the goldfish and carp, particularly the former; and. the Chi- 

 nese have already developed a number of special races bear- 

 ing distinctive names, and characterized, among other feat- 

 ures, by the possession of an extra number of tails. 18 A, 

 January 2, 1874, 382. 



HEREDITARY TRANSMISSION OF PHYSICAL PECULIARITIES. 



As a contribution to the question of the hereditary trans- 

 mission of physical peculiarities, it may be stated that, at a 

 meeting of the Physiological Society of London, Mr. E. Ward 

 exhibited two feet of a fawn, the mother of which had double 

 hind-feet, and had for several years brought forth young hav- 

 ing the same malformation. Proc. Zool. Soc, London, Jan- 

 uary 20, 1874. 



RAPIDITY OF THE ACTION OF THE NERVES. 



Some experiments have recently been made by Exner to 

 determine the reaction time of the sensorium ; that is to say, 

 the time required to convey an impression along the nerves 

 to the brain, and to convey an order from the brain to any 

 portion of the body, together with the interval required by 

 the brain to deliberate and act. Exner's method of observa- 

 tion consisted in stimulating some portion of the body, and 

 requiring the person immediately to make a signal "by press- 

 ing a telegraphic key with the right hand. Marks were pro- 

 duced on a blackened cylinder, both at stimulation and at sig- 



