588 Werner, Nochmals Mimikry und Schutzfärbung. 



stand these pieces teleologically. What is it that determines that locali- 

 zation shall occur at all in these pieces? It certainly cannot be the 

 „entelechy", and if not then typical localization of morphogenetic pro- 

 cesses is possible in Tubularia without the guidance of the entelechy. 

 If it is possible in these short pieces, why not in other long pieces? 



The phenomena of regulation in these short pieces show most 

 clearly that Dries ch's sharp distinction between the „typical" 

 and „atypical" in form is not only useless but false as regards 

 Tubularia, for structures wich Driesch regards as typical, i. e., 

 the hydranths of reduced lenglh with stems actually show the same cha- 

 racteristic, viz., a greater decrease in proximal than in distal structures 

 with decreasing length of the stem, which leads in still shorter pieces 

 to the formation of stemless hydranths and distal partial structures. 



To sum up concerning short pieces: Both Dries ch's measure- 

 ments and my own show that in pieces below a certain length 

 the localization of each „effect" or part of the primor- 

 dium differs typically in its relative position in the piece 

 with every further decrease in the length of the piece. 

 Proportionality between the length of the primordium and the 

 length of the piece is therefore not even approximately maintained 

 if I unterstand the word „approximately" but changes in a typical 

 direction. 



It should also perhaps be noted that this change cannot be 

 accounted for by the fact that hydranth-primordia of different sizes 

 arise within the perisarc, which is of approximately the same diameter 

 in all cases (cf. Driesch, 1901, p. 174). If the differences were 

 due to this factor, we should expect the measurements to show 

 that the length of the primordia decreased more rapidly than the 

 length of the piece, but as a matter of fact, the measurements 

 show exactly the opposite. I mention this point because Driesch, 

 in his criticism of ray work (Driesch, 1908, p. 4l3f footnote 1) 

 has called attention to his earlier statements upon this point. The 

 quotations which Driesch gives from his earlier papers (Driesch, 

 1908, p. 411) do not help the matter, so far as I can see, for they 

 do not concern the real point involved. I believe I have answered 

 his questions fully as to where he has made the assertions concerning 

 which he inquires. (Schluss folgt.) 



Nochmals Mimikry und Schutzfärbung. 

 Von Dr. Franz Werner. 



(Schluss.) 



IV. 



Es ist selbstverständlich, dass ein Tier besser geschützt ist, 

 wenn es eine Anpassungsfärbung trägt, als im anderen Falle. Aber 

 welchen Tieren fehlt sie? 



