LAWS OF HEREDITY. 13 



is termed an accidental variation from the established type — a, sport, as it is 

 frequently called. The color of the American deer is of a fixed type, and a 

 departure from this color is justly regarded as a great curiosity; yet, a white 

 deer is occasionally found ; and so of other animals in which the color is an 

 equally well-established characteristic. Man has five fingers on each hand 

 and five toes on each foot, and in this particular the race is uniform ; and yet 

 a " sport " is occasionally found, where the number of fingers or toes is 

 increased to six. When these accidental variations once occur, they are liable, 

 under favorable conditions, to be transmitted by inheritance ; but under the 

 ordinary operations of Nature's laws, when the conditions of life remain un- 

 changed, these anomalies usually disappear within one or two generations, 

 and the normal and characteristic type of the race is resumed. A well-authen- 

 ticated instance of the transmission of accidental variations is found in the 

 oft-quoted case of Edward Lambert, whose whole body, with the exception of 

 the face, the soles of the feet, and the palms of the hands, was covered with a 

 sort of horny excrescence, which was periodically moulted. His six sons all 

 inherited the same peculiarity, and the only one of the six that survived trans- 

 mitted it, in turn, to all his sons. This abnormal character was transmitted 

 through the male line for six generations, and then disappeared. We have 

 also several well-authenticated cases of the transmission, for a few generations, 

 of an abnormal number of fingers or toes ; as in the case of the Colburn family 

 where each of the members had a supernumerary toe and finger, Avhich 

 anomaly was transmitted, although irregularly, for four generations before it 

 entirely disappeared. The writer is personally cognizant of a case in which 

 the second and third toe of each foot were united, and which anomaly has 

 been transmitted for three generations to one only, out of an average of eight 

 descendants in each family. But, as before remarked, when the conditions of 

 life remain unchanged, these anomalies almost invariably disappear, and the 

 descendants resume the typical character of the race. 



From the fact that these accidental variations have shown themselves to be, 

 in a limited degree, transmissible by heredity, we may infer that if selections 

 were made with a view to their perpetuation, they might ultimately become 

 fixed characters — but of this more hereafter. Indeed, there is a considerable 

 weight of evidence tending to show that even variations produced by mutila- 

 tion, or by other artificial means, are sometimes transmitted, especially when 

 the mutilation has been intimately connected with the nervous system. Dr. 

 Prosper Lucas gives numerous well-authenticated instances of this character, 

 and is decidedly of the opinion that variations or mutilations that are the 

 result of disease, are transmissible. That eminent scientist. Dr. Brown- 

 Sequard, gives an interesting account of some experiments with guinea pigs. 

 By an operation upon a certain nerve, he produced epileptic convulsions, and 

 the produce of the animals upon w' hich this operation was performed mani- 

 fested the same symptoms. But notwithstanding the numerous instances 

 given by the eminent authorities above quoted, we are of the opinion that the 

 cases of the transmission of these artificially produced variations are so rare 

 as to be practically of no account in the calculation of the breeder. 



The law which governs the transmission of these accidental variations, 



