356 LIBBIE H. HYMAN. 



one result and on another occasion the contrary result. Loeb 

 has chosen to disregard the one contrary experiment since later 

 ("Organism as a Whole," p. 171), he again asserts, in spite of all 

 the evidence at that time available to the contrary, that apical 

 and basal pieces of the stem of Tubularia regenerate hydranths 

 simultaneously. This statement has never been confirmed, ex- 

 cept by Banus; every other zoologist who has worked upon the 

 matter has found the contrary to be true. In 1899, Driesch 

 working also at Naples expressed himself as fully convinced 

 that Loeb was mistaken. He found many evidences of regional 

 differences in Tubularia. He observed that the length of the 

 primordium is greater the nearer the piece is to the original distal 

 end of the stem; that in very small pieces, the more apical 

 pieces produce larger hydranths and tend to give rise to distal 

 structures only, while the basal pieces produce smaller hydranths 

 and proximal structures; and that when long pieces of the stem 

 are cut in half, the apical halves give rise to oral hydranths 

 earlier than the basal halves. Driesch, therefore, as he em- 

 phatically stated in this paper, disagreed with Loeb on this 

 point. In Table X, p. 131, Driesch gives a record of thirty 

 pieces in which the apical halves regenerated oral hydranths 

 one to twenty-three hours earlier than the basal halves in twenty- 

 five cases and simultaneously with them in but five cases. 

 Table XI, p. 132, presents similar data. These statements of 

 Driesch were verified by Morgan ('01, '05, 'o6a, '08), and by 

 Morgan and Stevens ('04). Thus Morgan says ('05, p. 496), 

 "the rate of both oral and aboral development is determined 

 by the level at which the end lies." Again in 1906, p. 497, he 

 states: "It has been shown in Tubularia that the time required 

 for the formation of a new hydranth depends on the distance of 

 the cut surface from the old hydranth. The nearer the cut 

 surface to the oral end the quicker the regeneration. The same 

 law also holds for the development of the aboral hydranth from 

 the aboral end of a piece." These statements were reiterated in 

 1908, p. 157 physiologically polarity is "shown in the more 

 rapid regeneration of the cut surfaces the nearer they are to the 

 distal end." 



Child ('07) again performed the experiment in question and 



