34 THE MENDEL JOURNAL 



instance, the torelimbs of both ox and man grow 

 greatly in response to use, but the lines of growth are 

 very different. Exactly. Of course, Dr. Reid 

 assumes that the difference in the power of making 

 acquirements is due to natural selection. The power 

 of growth in response to exercise resides, he says, not 

 especially in the parts which are most used, as joints, 

 teeth, or tongue, but in the parts in which it is most 

 useful ; in other words, in those parts where it has 

 been evolved, not by use, but by natural selection. 

 It would be difficult to compress a greater number of 

 fallacies into such few words. The chief fallacy lies 

 in the word use. Use of a muscle means contraction, 

 and contraction causes growth of muscle ; but it is 

 obvious that joints do not contract, and that a joint 

 has no size. The fact that joints can be developed 

 by use is proved by their actual formation occa- 

 sionally in neglected fractures. It is also obvious 

 that the tongue being a muscular organ is developed 

 by exercise not merely in absolute size, but in the 

 complexity and precision of its movements, as in the 

 muscles of the hand ; otherwise we could not learn 

 to speak. In fact, it is precisely because the power 

 of acquiring certain structural adaptations resides in 

 those parts which are used for certain purposes that 

 Lamarckians conclude that the power to acquire 

 and the acquirement are due to the same causes ; 

 in other words, that the hereditary or congenital 

 factor and the acquired factor in adaptations are both 

 due to external stimuli. The contrary view is mere 

 assertion based on no evidence. What evidence, for 



