80 THE CHANGES PROM STAGE A TO P. 



regard as one or two blunders in his description of its 

 devevelopment. 



He says (No. 30, p. 38), " Von alien Theilen der friiheren 

 Segraentblase behalt nur der 3. Abschnitt, die blindsackartige 

 Ausstiilpung, ihren Charakter, indem dort die Zellen als 

 Epithel angeordnet sich erbalten ; er wird zum Trichter des 

 Segmentalorgans." Again, on p. 45, " Man findet ihn (seg- 

 mental trichter of salivary gland) an seiner alten Stelle, 

 allenfalls ein wenig weiter nach hinten verschoben, als kurzen 

 Blindsac, welcher von seiner Ansatzstelle aus schrag nach 

 vorn dicht am eigentlichen Kanal der Speicheldriise hin 

 verlauft, nun aber nicht mehr mii Raumen des Lateralsinus 

 communicirt , sondern blind geschlossen ist " (my italics). 



Combining these passages with a statement on p. 38 as to 

 the breaking up of the Segmentblase of the oral papilla, it seems 

 clear that Kennel imagines ; (1) that the third somite does not 

 divide into a median and lateral part (though it does so in 

 other somites). (2) That the somite itself breaks up entirely 

 into a system of spaces, of which the lateral sinus is part. 

 This is implied by the first of the above quotations, and the 

 italicised parts of the second. It is also definitely stated on 

 p. 176 of Th. 1 (No. 29) in the following words : " Letzere 

 (i.e. Segmentalhohle) werden spater ganzlich in den Lateral- 

 sinus und die Hohlung der Fiisschen umgewandelt und geben 

 den Hohlorganen daselbst, besonders den Segmentalorganen 

 z. Th. der Ursprung." (3) That the funnel of the salivary 

 gland becomes closed and persists in life as a vesicle. (4) 

 (from other statements on p. 39) that the funnel of the 

 other nephridia are open throughout life into the broken-up 

 space of the foot (or lateral sinus?). 



I admit it is rather difficult to make out his exact meaning, 

 his account being somewhat confused and diflfuse. But I 

 think I am right in supposing that he maintains in the paper 

 referred to the above four positions. Well, accepting his idea 

 that the later stages resemble one another in the two species, 

 I have little hesitation in saying that he has erred in each par- 

 ticular. The third somite does divide into two parts. The 



