1909] 1,'itlir: Halocynthia johnsoni a., sp. 85 



given axis and generation is a quite different matter from thai 

 of the validity of such a law for all tentacles and all branches. 



So much for questions as to further "law and order" in the 

 development of tentacles in the same individual <nt<! in this one 

 species. Two questions, likewise unanswered for the present, 

 touching these organs in other species, may now he asked: Be- 

 cause there is a definite scheme of tentacle techtonic recognizable 

 in this species, dues it follow that such would be the case for all 

 other ascidians with branched tentacles? I should surely expect 

 so, though an examination of published figures by various auth- 

 ors, myself with the rest, gives the impression that this is nut so. 

 The fact is significant. Is there a definite plan of branching in 

 some ascidians and nut in others, or have we been in the habit of 

 simply ignoring the existence of such a plan; in other words of 

 regarding the fact of tentacle branching '"in a general way*' 

 only .' The probabilities are clear. The facts can he easily ascer- 

 tained by future observations. 



The other question of inter-species scope that we may ask is: 

 Presuming a plan of branching to prevail in all ascidians with 

 compound tentacles, would specific characters be found in these 

 schemes;' Hitherto systeniatists have made little or no search 

 for such characters in connection with these organs excepting as 

 regards their number. As suggested in the section on tentacle 

 structure, it is highly probable that such characters could be 

 found in some cases at least, were a quantitative study of the 

 tentacles made with reference to all accessible points in which 

 rules of multiplication prevail. 



Having swung into mid-stream in the quest after "law and 

 order" in the development and structure of this ascidian, it is 

 truly surprising to find how swiftly and smoothly we are borne 

 along. To the recognition that rules of sonic sort do prevail in 

 the enlargement and multiplication of parts there seems almost 

 no limit. Exactly what tin si rules are is quite another matter. 

 On this latter point I shall make a few remarks at the end of 

 this section. 



Only one other instance of probable orderliness will we look 

 at in this study. Attention has been called to the fact that the 



