380 chas. w. hargitt. 



Addenda and Discussion. 



As mentioned in the introduction the immeditae occasion 

 leading to the publication of this paper at this time after having 

 been laid aside for four years was the appearance in the Journal 

 of the Marine Biological Association, October, 1914, of a paper by 

 DeMorgan and Drew, setting forth the results of similar experi- 

 ments, all of which had given generally negative results. More- 

 over, certain of their conclusions seemed to leave a measure of 

 doubt concerning the conclusiveness of certain of Wilson's 

 experiments, and phases of their discussion involved assumptions 

 which are at variance with those which my own work had 

 rendered very convincing. 



In the first place I desire to refer briefly to Wilson's methods 

 and results with most of which my own are in accord. His 

 experiments on Eudendrium seem to have been much more 

 successful than my own, for which I am very glad, since it confirms 

 with great certainty points which in my own experiments were 

 incomplete, though sufficiently complete to warrant definite 

 conclusions. In another point Wilson's work goes beyond my 

 own, namely, in the admirable demonstration which his actual 

 sections of various stages affords as to the precise features 

 involved in the regenerative process at given times. Further- 

 more, the excellent series of drawings and photographs illustrating 

 his results leave nothing to be desired in that respect, and I am 

 purposely omitting any of my own, the only series of which not 

 better covered are those relating to Podocoryne, and in these 

 nothing essentially different occurs. 



The work of DeMorgan and Drew covered experiments on 

 two species of Antennularia and are restricted to these only. 

 In order to consider certain of their views it may be well to first 

 quote certain specific statements in their own words. "Our 

 results largely bear out his (Wilson) contentions, though we 

 were not successful in carrying the regenerative process as far 

 as the production of new hydranths, and the histological struc- 

 ture of the restitution masses we obtained differed in many ways 

 from that described in Wilson's paper. These differences are 

 probably due to the fact that we experimented with other species 

 of hydroids to those used by Wilson. The especial interest of 



