If it be asked why, on Lamarck's theory, if serpents wanted more legs they could not have made them, the answer is that the attempt to do this would be to unsettle a question which had been already so long settled, that it would be impossible to reopen it. The animal must adapt itself to four legs, or must get rid of all or some of them if it does not like them; but it has stood so long committed to the theory that if there are to be legs at all, there are to be not more than four, that it is impossible for it now to see this matter in any other light. The experiments of M. Brown Sequard on guinea pigs, quoted by Mr. Darwin,[298] suggest that the form of the serpent may be due to its having lost its legs by successive accidents in squeezing through narrow places, and that the wounds having been followed by disease, the creature may have bitten the limbs off, in which case the loss might have been very readily transmitted to offspring; the animal would accordingly take to a sinuous mode of progression that would doubtless in time elongate the body still further. M. Brown Sequard "carefully recorded" thirteen cases, and saw even a greater number, in which the loss of toes by guinea pigs which had gnawed their own toes off, was immediately transmitted to offspring. Accidents followed by disease seem to have been somewhat overlooked as a possible means of modification. The missing forefinger to the hand of the potto[299] would appear at first sight to have been lost by some such mishap. Returning to Lamarck, we find him saying:-- "Even in the lifetime of a single individual we can see organic changes in consequence of changed habits. Thus M. Tenon has constantly found the intestinal canal of drunkards to be greatly shorter than that of people who do not drink. This is due to the fact that habitual drunkards eat but little solid food, so that the stomach and intestines are more rarely distended. The same applies to people who lead studious and sedentary lives. The stomachs of such persons and of drunkards have little power, and a small quantity will fill them, while those of men who take plenty of exercise remain in full vigour and are even increased."[300] It becomes now necessary to establish the converse proposition, namely that:-- "_The frequent use of an organ increases its power; it even develops the organ itself, and makes it acquire dimensions and powers which it is not found to have in animals which make no use of such an organ._