Apbil 27, 1906.] 



SCIENCE. 



667 



Mr. Austin H. Clark read the last paper of 

 the meeting, describing ' A Case of Melanism 

 in West Indian Honey Creepers.' 



M. C. Marsh, 

 Recording Secretary. 



DISCUSSION AND C0BBE8P0NDENCE. 

 DR. O. F. cook's conception OF EVOLUTION. 



In Science, March 30, 1906, p. 506, Dr. 0. 

 F. Cook expresses the opinion that in the re- 

 cent discussion of isolation as an evolutionary- 

 factor there is ' a need of a simple distinction,' 

 and asserts that isolation does not play a part 

 in evolution. A similar idea, that neither 

 isolation nor natural selection nor mutation 

 factors in evolution, had been maintained 

 by him previously in a series of publications, 

 the last of which is a paper printed by the 

 Washington Academy of Sciences.' 



This astonishing view should be carefully 

 investigated and analyzed, for up to the pres- 

 ent time every writer on evolutionary subjects, 

 no matter what his standpoint, has taken it 

 for granted that any of the factors introduced, 

 if they are admitted at all, are admitted on 

 the ground that they are factors cooperating 

 in the general process called evolution. Dr. 

 Cook, however, believes that isolation, natural 

 selection, mutation, etc., have nothing to do 

 with evolution, and that the last is a different 

 process, due to ' causes resident in species.' 



Looking more closely upon his views, it 

 becomes evident that Dr. Cook's conception 

 of ' evolution ' is different from that of other 

 writers, and, of course, the propriety of his 

 criticism of the latter depends on the correct- 

 ness of his new conception of evolution. 



As every student of evolution knows, and 

 as also Dr. Cook admits,^ ' evolution,' as the 

 word implies, was originally intended to char- 

 acterize the whole process by which the or- 

 ganic world has been formed. According to 

 the view of Linnaeus, the organic world, as it 

 now exists, divided up in species, was created 



'0. F. Cook, 'The Vital Fabric of Descent,' 

 Proc. Wash. Acad. Sci., 7, Marcli 19, 1906, p. 

 301 ff. 



^ O. F. Cook, ' Evolution not the Origin of 

 Species,' Pop. Sci. Mo., 64, 1904, p. 445. 



so, and the number of existing species has 

 remained permanent since their creation; ac- 

 cording to Cuvier, a number of successive 

 creations of species have taken place, each de- 

 stroyed by a catastrophe. The ' theory of 

 evolution ' is opposed to the assujnption of a 

 permanency or stability, and introduces the 

 view that the present organic world has devel- 

 oped out of preexisting forms, the former be- 

 ing evolved, or developed, or descended from 

 the latter, and it admits the possibility of the 

 splitting up of one species into two or more. 

 Thus 'evolution' becomes a concept contrary 

 to permanency or stability, and expresses the 

 belief that organisms have reached their pres- 

 ent state by degrees, by a change or trans- 

 mutation, which they have undergone during 

 the process of descent from their ancestors, 

 connected with a differentiation. Since this 

 theory has been proposed in order to explain 

 the present condition of things, chiefly the 

 separation of the organic world into a large 

 number of species, the whole process of evolu- 

 tion has been called by Darwin 'origin of 

 species,' and Darwin's theory is known as 

 the ' theory of evolution,' or the ' theory of 

 descent,' and the terms ' evolution,' ' descent,' 

 ' development ' have been used as synonyms. 



But this is wrong, according to Dr. Cook. 

 Already Darwin's phrase ' origin of species ' 

 (the ' species-origination box,' as Dr. Cook 

 very elegantly calls it) does not include the 

 factor of ' evolution,' for evolution is different 

 from ' speciation,' or the making of species. 

 Evolution is a ' process of organic change and 

 development, universal and continuous ' ; it is 

 a ' continuous progressive change ' ; it is the 

 ' progressive development of organisms ' ; it is 

 a ' process of change in species ' ; which means 

 to say that it is characterized by a continuous 

 change of the organisms, which becomes evi- 

 dent and visible by the fact that the descend- 

 ants differ from their ancestors. This change 

 observed in the organic world is paramount in 

 Dr. Cook's conception of ' evolution ' ; he re- 

 stricts this term thus, and uses it exclusively 

 to express this fact. What happens later to 

 the changed organisms through the action of 

 natural selection, segregation, etc., is entirely 



