REGENERATION IN TUBULARIA CROCEA. 



305 



TABLE XXI. 



TABLE XXII. 



The results of these experiments confirm those obtained by 

 Morgan in every respect, as double structures were produced 

 very rarely, only one being obtained in the entire series of 

 experiments. There seemed to be no distinctive individual dif- 

 ferences in the pieces of stem as regards the structures produced. 

 In only one case (Table XIX.) were as many as three hydranths 

 produced, while in the tables given by Morgan for Tubularia 

 mesembryanthcimini, whole series of pieces from the same stem 

 produced hydranths. 



If a comparison is made between the results shown in Tables 

 XI. to XXII. and those shown in Tables V. to X., the most 

 noticeable difference is that a very much greater number of 

 double structures were produced when short pieces of the stem 

 were lying on their sides during the process of regeneration. In 

 both sets of experiments single proboscides were the structures 

 most frequently produced, and very little individual difference 

 could be detected in the stems regarding the kind of structure 

 that they would tend to produce. 



The development of small pieces of the stem of Tiilndana 

 standing on one end is considerably slower than that of similar 

 pieces lying on one side. In the latter case, development takes 

 place in about two days ; while in the former case the various 

 structures never appear under three days, and usually not under 

 four or five days. Many pieces, usually those nearer the proxi- 



