OTHER THEORIES OF SPECIES-FORMING. 323 



genesis. On the double basis of progressively less variation and of 

 the thus produced orthogenesis the author sees a factor in phylogeny 

 (organic evolution) which works, to some degree, independently of 

 natural selection or of Lamarckian factors. Rosa thinks he has 

 thus contributed to biology one of the always sought-for "unknown 

 factors in evolution." 



17 In an interesting paper by Snodgrass, 'The Relation of the Food 

 to the Size and Shape of the Bill in the Galapagos Genus Geospiza," 



Snodgrass's Auk > Vo1 - XIX > PP- 367-381, 1902, detailing the ex- 

 observations on amination of the stomach contents of over 200 indi- 

 billsofGala- viduals, representing 13 species and sub-species (taken 

 pagos 11 s, from several of the Galapagos Islands) of the peculiar 

 Galapagos Fringillid genus, Geospiza, remarkable for the great 

 differences in size and shape of bill characterising the various 

 species and sub-species, the author states that all the "evidence 

 seems to be in favour of the general conclusion that there is no 

 correlation between the food and the size and shape of the bill." 

 The following five propositions were established: (i) The same 

 species at different localities may feed on different seeds; (2) 

 different species at the same locality may feed on the same kinds 

 of seeds; (3) different species at different localities may feed on 

 the same kinds of seeds; (4) different species at the same or at 

 different localities may feed on different seeds; and (5) birds 

 with small bills eat only small seeds; birds with large bills eat both 

 small and large seeds. The seeds taken from the stomachs varied 

 in size from seeds of I cubic millimetre up to those 15 mm. long 

 by 10 mm. thick. The bill of the different species and sub-species 

 of Geospiza, varies from that of G. scandens scandens, 13 mm. 

 long by 7 mm. high at base, to that of G. pachyrhyncha, 17 mm. 

 long by 20 mm. high at base. 



18 Eimer, Th., "Orthogenesis der Schmetterlinge," 1897. 



19 Cope, E. D., "The Method of Creation of Organic Types," 

 Proc. Amer. Phil. Soc., December, 1871. 



20 Cope, E. D., "The Energy of Life Evolution," Pop. Sci. Mo., 

 Vol. XXVII, pp. 789-800, October, 1885: "Primary Factors of 

 Organic Evolution," 1896. 



21 "Palaeontologists, as a rule, and Prof. Cope is one of them, 

 are so profoundly impressed by the adaptive nature of the evolu- 



Oope's belief tionary process and by the definitiveness of its direc- 

 in orthogenetic tion, that they cannot regard the restraining or 

 evolution. selective action of the environment as enough to keep 



the breed true. They are so accustomed to seeing mutation after 

 mutation, generation after generation, developing in apparent obe- 

 dience to obvious physico-chemical or mechanical conditions, that 



