302 SCIENCE PROGRESS 



tainly not new, nor is the occurrence of a " group " of these mutants numbering 

 fifty collected from two or three adjoining houses a startling or new pheno- 

 menon. That such mutants when paired breed true was known long before 

 the days of Dr. Lloyd, and that if a pair of these mutants escaped to a desert 

 island they might give rise to what would be described as a new species 

 must also be admitted ; but they have not done so. May I refer Mr. Huxley 

 to a still older book than Lloyd's, viz. Wallace's Island Life, for proof that 

 the degree of distinctness of island forms from their nearest continental 

 allies is a function of the time of isolation, and points unmistakably to 

 progressive modification and not to mutation ? 



5. In support of his contention that specific differences are due to the 

 accidental action of " modifying factors," ^Ir. Huxley refers me to Cramp- 

 ton's work on a Tahitian genus of land-snails. Again I must refer Mr. Huxley 

 to Wallace. In oceanic islands, which consist essentially of volcanic cones 

 trenched by radial valleys, it has long been known that endemic genera of 

 land-snails exhibit an extraordinary multiplicity of species with exceedingly 

 limited ranges. To show in each case the functional significance of specific 

 marks is of course impossible, but let me remiud Mr. Huxley of what that 

 Nestor of British zoologists, Sir Ray Lankester, has well said : "A character 

 may either be directly useful or it may be the outward and visible sign of 

 an inner physiological grace." It is infinitely more likely that the specific 

 marks of the Tahitian species are symptoms of the constitutions that fit 

 them to their surroundings, rather than that these differences are due to 

 " accidental mutations," for it is not easy in the latter case to explain why 

 one species does not spread into the area of another, and by crossing with it 

 produce a mixed population. 



6. Mr. Huxley accuses me of objecting to " geneticists " thinking physio- 

 logically. My objection is that " geneticists " as a rule do not think physio- 

 logically, but treat the bodies of animals as picture puzzles in which the 

 parts can be shoved about and exchanged at will ; but I have a further 

 and radical objection to the tacit monopolisation of the term " geneticist " 

 by a limited group of Mendelian experimenters. Every zoologist worth his 

 salt is a geneticist; for the great root problem of his science is the discovery 

 of the causes and conditions of alterations in Heredity. Mr. Huxley compares 

 his " unit-factors " to the differences between chemical molecules, and the 

 reactions between organs — in a word, the action of the internal environment — 

 to chemical " mass-action." I have tried to point out that this conception is 

 radically false, that the divergences of the Mendelian mutants from the type 

 give no indication of the steps by which that type was built up. They are no 

 more units than are the fragments into which the mechanism of a watch 

 would be pounded by blows of a hammer. Such fragments would give no 

 indication of the means by which the wheel-trains of the watch had been 

 put together. 



7. Mr. Huxley can still see no reason for using Guyer's work as a support 

 to Lamarckism. I must say that he appears to me to be singularly dense 

 in this respect. The essence of Lamarckism, as I have repeatedly pointed out, 

 is the theory that the soma can influence the germ, and this theory certainly 

 involves the assumption that the essential constituents of the organs of the 

 body are somehow represented in the germ. This is precisely what Mr. 

 Huxley assumes ; he says : " If one or all of these [factors concerned in lens 

 production] are of the same composition as the proteins of the lens," then 

 the cytolysins which attack the one will attack the other. Incidentally, 

 Mendelians always seek in this way to escape the force of evidence that ac- 

 quired characters are sometimes transmitted : they maintain that the original 

 cause which modified the body modified the germ-cells at the same time. 

 The shallowness and far-fetched character of such assumptions has already 

 been alluded to by me in my original article. Guyer points out that, if 



