430 The American Naturalist [May, 



body can reproduce the entire organism. A branch of willow placed 

 in water develops roots at the expense of cells, which thus come to play 

 a part quite different to what was laid out for them in the original 

 plant, a proof, that is, that they already possessed this property from 

 their conception. On the other hand, a severed root may give rise fa) 

 buds which bear male and female organs ; so that sexual cells may be 

 derived directly from the cellular substance of a root. The epidermk 

 cells of a Begonia may produce an entirely new plant just as with 

 coelenterates, worms and tunicates, new individuals may come from 

 buds or separate parts of the body of these animals. These facts are 

 trite enough," he adds, " but it is well to recall them to show the solid 

 basis of Hertwig's conclusion that, ' the nucleus, by reason of the phe- 

 nomena it presents during fecundation, is the support or conservator 

 of hereditary properties and that it reappears in the same form and 

 with the same properties in every cell ; that it is a substance removed 

 from the grosser metamorphoses of matter by its inclusion in a special 

 vesicle; that by a complex mode of division the daughter nuclei 

 receive portions of the same substance, no diilcrentintion 

 Just as Nageli claims that his hypothetical idioplasm is spread 

 throughout the body like a fine net-work, so according to my theory, 

 every cell of the body encloses in its nucleus the aggregation of hereditary 

 properties derived from the egg, whilst the specific properties of &« 

 cell are bound up with the development of the protoplas 

 consequently every cell possesses the faculty, under appropriate con v 

 tions of reproducing the entire organism.' "— B. W. Barton, M. D-> 

 Johns Hopkins University, Baltimore, Md. 



