118 STUDIES IN GENERAL PHYSIOLOGY 



Almost all the numerous other authors who have worked 

 upon the regeneration of organs in animals also regard it as 

 self-evident that the regenerated organ must be identical 

 with the lost organ in form and function. The facts which 

 I shall bring forward in the following pages will show, how- 

 ever, that this theory is certainly too narrow. For I suc- 

 ceeded in doing away with "polarity" first of all in that 

 very animal upon which Allman based his theory of 

 "polarity" namely, in Tubularia. 



One of the first authors who concerned himself with 

 the study of the phenomena of regeneration, Charles .Bonnet, 

 looked upon them in a less biased way than did Allman. 

 Bonnet, to whom Trembley had very early communicated 

 the fact of the phenomenal regenerating power in Hydra, 

 attempted to convince himself of the truth of Trembley's 

 statements; since, however/ he was unable to obtain Hydra, 

 he tried whether similar results could not be obtained upon 

 worms. Bonnet used two species of worms in his experi- 

 ments. In the first species, which he designates as vers 

 rouge&tres, he found the conditions which are typical for 

 Hydra, and which correspond to the theory of "polarity." 

 If the head of such a worm was cut off, a new head was 

 formed at the cut end ; when the tail was cut off, a new tail 

 was formed at the point of section. If the head and tail 

 were both cut off, a head was formed at the oral end, and a 

 tail at the aboral end. In a second species, the vers 

 blanch&tres, the results were not so regular. When only 

 the head or tail was cut off, the lost part was always 

 regenerated. If, however, a piece was cut out of the middle 

 of the worm, it happened that such a piece formed a tail at the 

 oral end, instead of a head. Bonnet observed this three times. ' 

 I have found no reference in the literature which would 

 indicate that these observations of Bonnet have ever been 



iCn. BONNET, (Euvres d'histoire naturelle et de philosophic (Neuchatel, 1779), 

 Vol. I (TraitS cTinsectologie). 



