68 KTIKNM; CJKOFFKOY SAINT-HILAIRE 



brought in its train successive changes in the proportion of 

 the different elements of the atmosphere, it follows as a 

 rigorously necessary consequence that the organisation has 

 been proportionately influenced by them" (p. 76). The 

 respiratory milieu changes, the species change with it, or are 

 .eliminated (p. 79). We may see, perhaps, in the stress which 

 Geoffroy lays upon respiration and the respiratory milieu 

 a result of his constant obsession with the comparison of fish 

 with air-breathing Vertebrates. 



In the first geological period, we read in another Memoir 

 of the same year, 1 when ammonites and GrypJuca flourished, 

 hot-blooded animals with lungs could not exist. " A lung 

 constructed like that of mammals and birds would not have 

 been adapted to the essence of the respiratory element such 

 as in my conception of it the system of the environing air 

 used to be"- (p. 58). 



Geoffroy does not tell us exactly how the milieu is to act 

 upon the organism ; the whole theory is little more than 

 a sketch and a pointing out of the way for future research 

 and in this prophetic enough. The action of external agents 

 was apparently considered as physical, and no power of 

 active adaptation was ascribed to the organism. 



From a passage in the memoir " Sur la Vertcbre " we 

 may perhaps infer that he believed increasing complexity of 

 structure to be due to a realisation of potentialities, to the 

 development of parts present in the lower animals only in 

 potency --" the organisation . . . only awaits favourable 

 conditions to rise, by addition of parts, from the simplicity 

 of the first formations to the complication of the creatures at 

 the head of the scale" (p. 112). Evolution takes place as 

 the environment allows, and in a sense in opposition to the 

 environment. 



Me believed in saltatory evolution, for he considered that 

 the lower oviparous Vertebrates could not be transformed 

 into birds by slow modification, but only by a sudden 

 transformation of their lungs, which would bring about the 

 other characteristics of birds (p. 80). He considered, too, 



1 M,'in. Ac<ui. Si'i., xii., ]>p. 43-61, 1833. 



- Geoffroy's French style is at times incredibly bad, and more or less 

 literal translations of his sentences are apt to read quecrly! 



