REPAIR IN EVOLUTION 91 



Graves' Disease, just as hyper- or hypopituitarism causes 

 giantism or infantilism in children, while a later overgrowth 

 of the gland causes acromegaly, I see no difficulty in accept- 

 ing the hypothesis that growth is determined, i.e. stimulated 

 or finally inhibited, by non-living catalysts or secretions 

 not necessarily confined to the endocrine organs. In this 

 way a bridge may perhaps be built between the orthodox 

 Weismannian and the Lamarckian. Growth and character 

 are caused by determinants ; but these are not parts of the 

 cytoplasm itself, they are the machinery by and through 

 which living matter acts. The organism is not built 

 up by special protoplasm, or by entelechies, or by any 

 mysterious elan creatif. It arises from the definite influence 

 of definite catalysts originating, in an orderly sequence, 

 as the organs become differentiated, while the individual 

 is as a whole exposed in an infinite progression to the 

 internal and external stimuli of a like but slowly changing 

 environment to which it reacts. The factors which did 

 the work are working now. 



To recapitulate the tentative conclusions arrived at, 

 it may be suggested that : 



i. Mechanical reaction to stress is a general law of all 

 tissues. 



2. Morbid conditions in many cases give rise to repair 

 which becomes physiological. 



3. Such repairs lead to new functions, new stresses, 

 further morbid states, and further repair. 



4. These factors are some of the main causes of specific 

 and generic differences. 



5. In all probability transmission of changes caused 

 in the way indicated takes place by a morphogenetic reply 

 in utero to increased functional stresses. 



6. As it is a narrow view to assume that pathology 



