Kyder.] ^^^ [Oct. 18, 



ju tlie near future. One may be still more sweeping and even offer good 

 reasons for the assertion that there is not now upon record a single 

 instance of structural modification due to mutilation which has been even 

 adequately traced or studied by the lielp of the rigorously exact onto- 

 genetic method. Experiments, in mutilating a few successive generations 

 of mice are of no value in deciding this question, first, partly for the 

 reasons already assigned, and, secondly, because there were not enough 

 successive generations experimented upon, and, thirdly, because there is 

 but little direct evidence to prove that structural alterations resulting 

 through external mutilation are inherited. To hold up the results of such 

 experiments as conclusive evidence against what are claimed to be the 

 erroneous views and grounds of opinion of Lamarck and his followers may 

 be regarded as scientific amongst Neo-Darwinists, but as a good old- 

 fashioned Lamarckian such a proceeding appears to me just the reverse. 



The evidence as to the effects of use in the modification of species was 

 very meagre in Lamarck's time, and but little evidence of a conclusive 

 character has been accumulated since, as is proved by the paucity of 

 examples cited even by Darwin himself. Even the cases of the dung- 

 beetles, where the tarsi of the anterior legs are completely lost in 

 Ateuchus, the sacred beetle, the evidence that their absence is due to the 

 inheritance of their very frequent loss through mutilation is uncertain. 

 Tlie only case where a mutilation seems to have been inherited is, as the 

 writer first pointed out, that of the imperfect enamel crowns of the 

 embryos of white rats studied by Von Briinn. In these cases the imper- 

 fection of the enamel coverings in the just erupting molars corresponded 

 exactly to the enamel areas worn off" through use at the tips of the crowns 

 in the molars of the adults. 



While it is impossible to subscribe to much that has been offered as 

 explanatory of structural modification through use alone, there are many 

 instances of structures the origin of which is to be accounted for in no 

 other way. The crude hypothesis of Herbert Spencer (" Prin. Biology," 

 ii, Chap, xv), as to the method of evolution of the vertebral column, while 

 far better than the transcendental speculations of Owen respecting the 

 general homologies of the vertebral bodies, wiih their appendages, can 

 now be replaced with a far better one. While it remains true, as Spencer 

 points out, that the segmentation of the vertebral axis is due, as even 

 Rathke and Balfour, recognized, to the mechanical requirements of such 

 an axis and the conditions of growth under which it is placed, the details 

 of this process have not even yet been fully worked out. In order to do 

 so the vertebral axis of every distinct type must be critically investigated ; 

 the processes of the ontogeny of every one of its elements, no matter how 

 minute, not simply its ontogeny, must be traced before comparisons and 

 deductions are in order. Over a year ago the pi'esent writer took up anew 

 the general subject of the vertebral column throughout the vertebrate 

 series, witli the result of finding that this structure is an example of con- 

 tinuous evolution as supposed by Herbert Spencer, in his article entitled 



