368 DARWINISM TO-DAY. 



possible explanation of the origin of particular species of plants, 

 but so far as known, not applicable in the case of animals." 



Certain naturalists even go so far as to express some doubt about 

 the value of the mutations observed by de Vries in the primroses. 

 This doubt touches two points. First, the possibility that the 

 mutating primroses are not pure cultures, but are hybrids; second, 

 that when an investigation of the wild primroses in their native 

 locality (southern United States) is made it may be found 

 that these primroses in true wild condition do not mutate. Touch- 

 ing these two points, it should be said that de Vries has convinced 

 himself that his cultures are pure, and has tried to discover the 

 actual conditions existent among the primroses in their native 

 habitat. As a matter of fact, the Lamarckian primrose seems to be 

 practically extinct as a wild species. De Vries ("Uber die Dauer 

 der Mutationsperiode bei CEnothera Lamarckiana," Ber. Deutsch. Bot. 

 Gcscll., Vol. XXIII, pp. 382-387, 1905) found specimens of (Enothera 

 Lamarckiana in three botanical collections in the United States. 

 These specimens were collected in Florida and Kentucky. How- 

 ever, since these specimens were taken (the Florida ones in 1860) 

 the species has not been observed, perhaps on account of lack of 

 close observation, perhaps because actually disappeared. There- 

 fore the question whether the Lamarckian primrose mutates in 

 wild condition remains undecided. 



:3 The most considerable critical discussion and analysis of the 

 mutations theory is that made by Plate in his review of Morgan's 

 Plate's criti- "Evolution and Adaptation. (Plate, L., '"Darwinismus 

 cism of the mu- kontra Mutationstheorie," Archiv f. Rassen- und Ci- 

 tations theory, sellschafts-Biologie, Vol. Ill, pp. 183-200, 1906.) In 

 the course of his critical review of Morgan's book (which book 

 is at once an attack on Darwinism and an upholding of the muta- 

 tions theory). Plate points out keenly and strongly the weak places 

 in de Vries's theory. As a general substitute for the natural selec- 

 tion theory as an explanation of adaptation as well as species-form- 

 ing, the mutations theory is open to many of the same objections as 

 the Darwinian theories. Plate takes up, serially, Morgan's claims 

 for the mutation theory and readily shows their unconvincing char- 

 acter. I quote some of this analysis, as follows : 



"Es ist von Interesse zu sehen, welche Grunde Morgan bestim- 

 men. der Mutationstheorie trotz ihrer fundamentalen Mangel den 

 Vorzug zu geben vor der alten Darwin'schen Auffassung. Auf. S. 

 298 zahlt er die 'Vorzuge' dieser Theorie auf, die aber meines 

 Erachtens alle vor der Kritik nicht standhalten. 



'' 'i. Da die Mutationen von Anfang an vollstandig ausgebildet 

 auftreten, fallt die Schwierigkeit fort, die Anfangsstadien in der 



