204 



DYNAMICS OF LIVING MATTER 



was made from a different point of view independently by Godlewski.* 

 Through the ligature the current which carries away substances from the 

 aboral end is inhibited, and hence the cause for the polarity is removed. 

 • When I first made these experiments the hypothesis of Sachs seemed 

 to suggest that in the excised piece of a stem not enough specific polj^- 

 forming material was present to allow the simultaneous forming of two 

 polyps, but the experiments already mentioned exclude this idea. It is 

 further excluded by the observations made by Miss Bickford, who 

 found that even if a stem be cut into a number of small pieces, each 

 oral end of such a piece forms a polyp. Hence it is not a question of 

 lack of material but only a lack of free cut ends, which block the flow 

 of sap, if only one polyp is formed in a piece cut from the stem of a 

 Tubularian. It is therefore apparently the process of streaming itseK 

 which may take something away from the aboral end, which is responsi^ 

 ble for the fact that a stolon is formed here, or if a polyp be formed that 

 its formation is delayed. 



As far as the method of regeneration is concerned, Miss Bickford 

 has found that it does not consist in the growth of a new polyp from 

 the old material, but in a direct transformation of the 

 material of the stem into a new polyp. Miss Bickford 

 observed this directly under the microscope in small 

 pieces from the stem of a Tubularian, which were not 

 even of the size of a normal polyp. In such cases the 

 whole mass of the piece was transformed into a polyp. f 

 In the case of the smallest pieces the result was still 

 more striking. At each free end of the small piece of 

 the stem tentacles and a proboscis were formed (Figs. 43 

 and 44), but inasmuch as there was no material left for 

 the formation of a stem in addition to two polyps, or 

 not even for two entire polyps, a kind of Janus head 

 was formed, two faces or probosces of a polyp looking 

 in opposite directions. No new outgrowth occurred, 

 but the old tissues arranged themselves into a new 

 shape, forming a polyp, while before they had formed 

 part of the stem. The most remarkable fact was the 

 transformation of certain cells of the entoderm into 

 secretory cells of the stomach. 



It is not yet possible to tell exhaustively which forces 

 have to do with this transformation. The stem is 

 surrounded by a chitinous layer. I have never observed the formation 



Fig. 43.— After 

 Miss Bickfokd. 



Beginning of the 

 formation of 

 two polyps in- 

 side a piece 

 from a stem of 

 Tubularia. 



* Godlewski, Archiv fur Entmickelungsmechanik, Vol. 18, p. 11 1, 1904. 

 t Elizabeth E. Bickford, yowr. of Morphology, Vol, 9, p. 417, 1894. 



