XVI ARE ACQUIRED CHARACTERS INHERITED ? 335 



ble circumstances. In his Factoids of Organic Evolution 

 he recurs to the subject, in order to exclude two imaginable 

 causes which he had not before referred to — a correlation 

 of decreased jaw with increased brain, which he rejects, 

 because many small-brained people are also small-jawed, 

 while others distinguished for their mental power have 

 yet jaws above the average size : and sexual selection, 

 which he also rejects for obvious and valid reasons. 



Subsequently, the same question was discussed by Mr. 

 W. Piatt Ball, in his excellent little work, Are the Effects of 

 Use and Disuse Inherited ? He shows that the difference 

 of size is less than has been supposed, while the great 

 range of variation in the size and weight of the jaw, both 

 in civilized and savage races, renders all comparisons use- 

 less unless founded on a very large number of specimens. 

 He then accounts for the reduction that actually exists by 

 a variety of suggested causes, some of which are undoubtedly 

 open to criticism. He also states that he " allows for a re- 

 duction proportional to that shown in the rest of the skull," 

 because some other agency than disuse must have reduced 

 the thickness of the skull, and, presumably, of the jaws 

 also; after which allowance there remains but a small 

 further reduction of the jaws to be accounted for. 



This portion of Mr. Piatt Ball's work called forth a very 

 minute criticism from Mr. F. Howard Collins, which, being 

 declined by the editor of Nature — as the author tells us in 

 his preface — has been published in pamphlet form. As Mr. 

 Collins is the author of An Epitome of the Synthetic Philo- 

 sophy, so well done as to have received the approval of Mr. 

 Spencer himself, he may be supposed to speak with some 

 authority when he undertakes to attack one of Mr. Spencer's 

 critics ; and for this reason I think it advisable to point 

 out the erroneous and illogical principles on which his 

 whole argument is founded. In order to compare the jaws 

 of Australians with those of recent Englishmen, he takes 

 one linear dimension of the jaws, cubed to get the propor- 

 tionate bulk, and compares this with the cubical contents 

 of the skulls to which the jaws belong, that is, with the 

 mass of the brain. Now, as the Australians have very 

 much smaller brains than Europeans, to compare the jaw 

 with the skull-capacity is \q make it appear much larger 



