ACQUIRED CHARACTERS 37 



peculiar condition resembling epilepsy, and this con- 

 dition appeared, in sorie few cases, in the offspring. 

 In one of the most striking cases the sciatic nerve had 

 been cut. The creatures of course lost sensation in 

 their hind limbs, with the result that many of them 

 gnawed off several of their hind toes. From these a 

 small proportion of offspring were obtained which lacked 

 several of their hind toes, or sometimes their whole 

 hind feet. 



Instances could be considerably multiplied, and a 

 well-marshalled array of such cases seems difficult to 

 explain away. Nevertheless, when positive results are 

 obtained only in a small percentage of cases, it is 

 necessary that we should look carefully for other 

 possible explanations, and the inheritance of acquired 

 characters is proved only when such other causes are 

 excluded. 



The cow with the ulcerated horn may well have had 

 a naturally imperfect horn, which was readily attacked 

 by disease, and the imperfection may have increased by 

 an inborn variation in the offspring. 



Brown-Sequard's conclusions, too, are open to criti- 

 cism. The operations by which epilepsy was produced 

 were very severe in their effects on the nervous system 

 and whole constitution of the animals, with the result 

 that few perfect young were produced. Many of the 

 young were classed as generally feeble, many showed 

 special defects in no way suggesting epilepsy, and a 

 few were epileptic. The appearance of these few 

 amongst a large number of imperfect offspring can 

 hardly be regarded as evidence that the epilepsy, as 

 such, was inherited. In the other case quoted the 

 explanation has been suggested that the toes of the 

 young guinea-pigs were actually perfect at birth, but 

 were afterwards gnawed off by their dams. It is known 

 that rodents occasionally show a tendency to gnaw the 

 tails or feet of their young, and it seems that this might 

 well occur, especially as the habit had been previously 

 somewhat developed. 



Again, a number of supposed cases of the inherit- 



