668 



SCIENCE. 



[N. S. Vol. III. No. 70. 



chemistry. A fellow in biology will also be ap- 

 pointed. 



The University of UtrecM will celebrate this 

 year its 260th anniversary, the fetes beginning 

 on June 22d. The many American students 

 and professors going abroad during the summer 

 will find this a favorable opportunity to visit 

 Utrecht. 



The late Mrs. Nichol, of Edinburgh, has be- 

 queathed $10,000 to Edinburgh University, to 

 found a scholarship in physics. 



Prof. J. Peery has been appointed to the 

 vacant chair of mechanics and mathematics at 

 the Royal College of Science, London. 



The University of Edinburgh has conferred 

 the degree of LL. D., on President F. A. 

 Walker, of the Massachusetts Institute of Tech- 

 nology. 



The Senate of Glasgow University has con- 

 ferred the degree of LL. D., on Prof. Thisel- 

 ton-Dyer and on Prof. Andrew Gray. 



De. Albeet Fleischmann has been pro- 

 moted to an assistant professorship in the Uniy 

 versity of Erlangen and has been appointed di- 

 rector of the Zoological Institute. Dr. George 

 Eorig, of the Agricultural High School at Berlin, 

 has been appointed assistant professor of zoology 

 in the University of Konigsberg. 



DISCUSSION AND CORRESPONDENCE. 



the material and the efficient causes 



of evolution. 



Peofessor Brooks states in the last number 

 of this journal that he is glad to find that after 

 much irrelevant discussion one reader (M. M. , 

 Science, Apr. 3d) has found the thesis of his 

 article on Science and Poetry (Science, Oct. 4, 

 1895) worthy of serious consideration. Now 

 it seems to me on the contrary that M. M. does 

 not discuss Professor Brooks' views, but simply 

 points out the ambiguity of his phrase ' test of 

 truth.' 



I should suppose that no one outside of a 

 madhouse would dispute Professor Brooks' view 

 that conceivability is not a sufficient test of 

 truth. Whether or not conceivability is a ne- 

 cessary condition of truth depends somewhat 

 on what is meant by ' conceivability, ' which 



is a comparatively new word, and is used by 

 Professor Brooks with some latitude. If it be 

 inconceivable to him that the image on the 

 retina is inverted, then of course conceivability 

 is not for him a necessary condition of truth. 

 Whether or not a proposition which would com- 

 monly be regarded as inconceivable — as that a 

 straight line may enclose an area — could in a 

 special case be proved true by evidence, and if 

 so whether the proposition would continue to 

 be inconceivable, are questions which M. M. 

 does not discuss. 



At the risk of again being accused of irrele- 

 vancy by Professor Brooks, neither shall I dis- 

 cuss these questions, but wish to make clear 

 a distinction analagous to that pointed out 

 by M. M. In discussions on the theory of evo- 

 lution we find Neo-Darwinians saying that 

 ' natural selection' is the cause of the origin of 

 species, and Neo-Lamarckians saying that the 

 environment and the movements of the ani- 

 mal are the causes of adaptations. Now in 

 these cases the word ' cause' is used ambigu- 

 ously, ignorance of the facts of evolution be- 

 ing concealed by the exhibition of ignorance of 

 logic. 



I wonder how many men of science have read 

 Aristotle, or understand his distinctions between 

 material, efficient, formal and final causes. We 

 are not here concerned with a formal cause, the 

 idea or plan of a thing, nor with a final cause, 

 the end for which it is made ; but no student 

 of organic evolution can afford to ignore the dis- 

 tinction between material and efficient causes, 

 or between the occasion and the efficient cause 

 of an event. The material cause is that of 

 which a thing is made, one of the occasions or 

 necessary conditions of its existence ; the effi- 

 cient cause is that which produces a thing and 

 makes it what it is. When no qualification is 

 used cause should mean efficient cause or vera 

 causa. 



' Natural selection ' is no cause of the origin 

 of species, but may be the cause of the anihila- 

 tion of unfit species. Whether or not the en- 

 vironment, or consciousness, or the movements 

 of animals are causes of hereditary modifica- 

 tions are open questions. What is called the 

 cause of an adaptation is, however, usuallj' only 

 its occasion. Thus at a recent meetinsr of the 



