616 A. A. W. HUBRECHT. 



form and in function^ and the foremost individual thus becom- 

 ing the head of the series. Each segment (metamere) thus 

 represents a reduced individual ; a metameric (segmented) 

 animal is the result of the more or less complete fusion of 

 single individuals into an individual of higher order." 



Emery, from whose paper^ I have translated the foregoing 

 sentence, has very successfully combated these propositions. 

 This author, however, adheres to Lang's views in ascribing to 

 the archenteric pouches, the " gemmation " as Emery calls it 

 (loc. cit., p. 18) of the intestine, the most important and 

 initial significance for the first origin of metamery, " the sex- 

 ual glands and excretory canals being in relation to the 

 intestinal diverticula," and following the lead. I have above 

 explained why I cannot adhere to this argumentation, which 

 brings the coelome and the sacculated intestine too strongly 

 into the foreground, and why I rather suppose incipient 

 metamery to have been antecedent to either of these (e.g. 

 Carinella). On the other hand, many views contained in 

 Emery's important paper coincide with my own. Thus he 

 writes (loc. cit. p. 11), speaking of that interesting marine 

 Triclade, Gunda segmentata: 



" The metamery of Gun da is thus manifestly the conse- 

 quence not of the 'symbiotic' fusion of a colony of equivalent 

 'parts' (meridi), but of the 'autobiotic' differentiation and 

 perfectioning of one 'part' (meride);" and further on (p. 15) : 

 — " When I consider the facility with which certain worms 

 break into one or more pieces even spontaneously, it appears 

 to me that this capacity for rupture may well have been the 

 origin of the reproductive purpose of transverse scission in 

 similar elongated organisms. The rupture, in the first instance 

 accidental, could have contributed to the more rapid multipli- 

 cation of the organism, being followed by the regeneration of 

 the parts that were deficient in the separate fragments. This 

 process of rupture might further have been so perfected that 

 the spot best adapted for rupture, with a view to the best con- 

 dition of the fragments, was prepared in advance. In the 

 ' C. Emery, ' Colonie lineare e metameria/ Napoli, 18S3. 



