i 9 6 SCIENCE PROGRESS 



enclosed in stone in quarries. It is unnecessary to discuss 

 seriously this suggestion : it will be sufficient to consider how 

 much foundation there is for the dictum of Dr. Reid, that the 

 frog's body gains nothing from use, and his mind almost nothing 

 from experience. This implies that the metamorphosis is 

 entirely due to heredity, and not at all to stimulation. It has 

 been proved, on the contrary, that aquatic larvae of Amphibians 

 can be made to retain the larval state by forcing them to 

 breathe in the water, and not allowing them to breathe air, so 

 that in this case, as in many others, the development is partly 

 due to acquirement in Dr. Reid's sense of the term. Dr. Reid 

 contrasts with the supposed development of the frog, the 

 alleged fact that if the limb of an infant be locked by paralysis 

 or by a joint disease, it does not develop into an adult limb, 

 but there is every reason to believe that the same statement 

 would be true of the frog. 



We must conclude then that man differs from the anthropoid 

 apes chiefly in adaptational characters, and that these characters 

 are inborn or congenital ; they are congenital in two senses : 

 first, in the sense that they develop to a certain degree 

 under what Dr. Reid calls the stimulus of nutrition, by which 

 he means nutrition, moisture, heat, and oxygen, the essential 

 conditions of all development and all life ; x secondly, that they 

 attain their adult development from an hereditary tendency to 

 certain modes of use and function, and from a degree of ex- 

 ercise which would not produce the same development in any 

 other species. The new-born infant differs from the adult man, 

 but it also differs from the new-born ape in all essential human 

 characters, and that adult has acquired structural peculiarities 

 which no ape could possibly acquire from any stimuli in its 

 own life-time. Obviously these are not merely specific char- 

 acters, and man is not merely a species of a wider genus. 

 Adaptational differences are characteristic among other animals 

 of a genus, or of a family, or of larger groups. For example, 

 among the mammals the Orders are distinguished by differences 

 of adaptation, e.g. the Cheiroptera and Carnivora ; but within a 



1 The antithesis on which Dr. Reid insists between characters developed under 

 the stimulus of nutrition and those developed under the stimulus of use is fallacious 

 and misleading. Nutrition, moisture, heat, and oxygen are necessary conditions 

 of all life : different characters develop under these same conditions, they deter- 

 mine the development of the organism, not of the characters ; whereas a particular 

 mode of use determines a particular character. 



