THE PROVISIONAL HYPOTHESIS OF PANGENESIS. 299 



"Wliewell, the historian of the inductive sciences, remarks, 

 " Hypotheses may often be of service to science when 

 they involve a certain portion of incompleteness, and 

 even of error." Under this point of view I venture to 

 advance the hypothesis of pangenesis, which implies that 

 every separate part of the whole organization reproduces 

 itself. So that ovules, spermatozoa, and pollen-grains — 

 the fertilized egg or seed, as well as buds — include and 

 consist of a multitude of germs thrown off from each 

 separate part or unit. 



FUNCTIONAL INDEPENDENCE OF THE UNITS OF THE 

 BODY. 



Physiologists agree that the whole organ- 

 ism consists of a multitude of elemental parts, 

 which are to a great extent independent of one another. 

 Each organ, says Claude Bernard, has its proper life, its 

 autonomy ; it can develop and reproduce itself independ- 

 ently of the adjoining tissues. A great German author- 

 ity, Virchow, asserts still more emphatically that each 

 system consists of an "enormous mass of minute centers 

 of action. . . . Every element has its own special action, 

 and, even though it derive its stimulus to activity from 

 other parts, yet alone effects the actual performance of 

 duties. . . . Every single epithelial and muscular fiber- 

 cell leads a sort of parasitical existence in relation to the 

 rest of the body. . . . Every single bone-corpuscle really 

 possesses conditions of nutrition peculiar to itself." Each 

 element, as Sir J. Paget remarks, lives its appointed time 

 and then dies, and is replaced after being cast off or ab- 

 sorbed. I presume that no physiologist doubts that, for 

 instance, each bone-corpuscle of the finger differs from 

 the corresponding corpuscle in the corresponding joint of 



