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THE AMERICAN NATURALIST [Vol. XLIII 



two processes. The off-hand way in which this fact is now 

 treated, as compared with the almost frantic contention of 

 twenty years ago that the two are fundamentally different, at 

 least in phylogenetic significance, may well be reflected upon 

 when our minds are turned toward theoretical biology. 



Regeneration: Under this head there are two valuable papers. 

 One ("An Experimental Study of the Rate of Regeneration in 

 Cassiopea xamachana") is by Chas. R. Stockard, and the other 

 ("Some Internal Factors concerned with the Regeneration of 

 the Chela? of the Gulf-weed Crab") is by Chas. Zeleny. Stock- 

 ard finds no support in this research for the hypothesis that 

 activity of the regenerating part accelerates or influences in any 

 special way the regeneration. By cutting pieces of various 

 shapes and sizes from the bell of the medusa, he gets the interest- 

 ing result that on the animal itself the "regeneration rate is 

 fastest from the portion from which most tissue has been re- 

 moved"; and on the pieces cut away regeneration is "fastest 

 from the part from which the least tissue has been removed." 

 The reviewer would raise the inquiry, Does not this conclusion 

 say essentially that the removed tissues of Cassiopea are replaced 

 in the way necessary to effect the quickest and surest restoration 

 of the original form of the animal regardless of the form and 

 place of the cut? 



Zeleny 's researches were directed at two fundamental points: 

 "The quantitative determination (1) of the effect of successive 

 removal of an organ upon its power to regenerate and (2) of the 

 character of the changes, if any, produced in the uninjured 

 parts of the animal by such removal. ' ' The summarized results 

 are: (1) ""When the correction for change in power of regenera- 

 tion with size or age is made it is found that successive removal 

 neither retards nor accelerates the regeneration of the right 

 chela." The criticism may be ventured that this conclusion is 

 too unqualified for the number of tests made, there having been 

 but three removals of the same chela in the same individual. 

 As we commit ourselves more and more to quantitative methods 

 in biology, we shall see more and more clearly, so it appears, 

 the importance of the principle of "large numbers." On the 

 second object of the research the result was: "The removal and 

 regeneration of the right chela produces no change in the growth 

 of the uninjured left chela." 



Faunal Zoology: The titles belonging primarily under this 

 head are: "The Pelagic Tunicata of the Gulf Stream," by W. 



