84 



Det er derfor sandsynligt, at han — ligesaalidt som 

 Kölliker — har havt Anledning til at anstille nogen 

 fuldstændigere anatomisk Undersøgelse. 



Kanalsystemet hos Ptilella grandis afviger noget fra 

 det, der ifølge Köllikers Beskrivelse tilhører Pennatuli- 

 derne ialmindelighed. Med Hensyn til Længdekanalerne 

 er at bemærke, at Ventralkanalen er temmelig smal; 

 Sidekanalerne, der omfatte Axen, ere hver for sig bredere, 

 og Dorsalkanalen mindst ligesaa bred, som begge disse 

 tilsammen. 



Dorsalkanalen gaar lige op til Spidsen af Rachis; 

 dette er ogsaa Tilfældet med Ventralkanalen; men denne 

 danner i en Afstand af 100 Mm. fra Spidsen en stærk 

 Udvidning (Fig. 4, 5 v') for at give Plads for den krum- 

 bøiede Axe (Fig. 4 a). Udvidningen er 30—40 Mm. lang 

 og omtr. 15 Mm. bred; ovenfor og nedenfor er Kanalen 

 kun 6 Mm. bred. Sidekanalerne (Fig. 4, 5 Sv Sh), der 

 omfatte Axen, gaa i sin fulde Bredde op til det Sted, 

 hvor Udvidningen paa Ventralkanalen og Krumningen af 

 Axen begynder. Idet Axen krummer sig, udspiles dens 

 Skede saaledes, at den danner en Dobbeltmembran, der 

 er stramt udspændt, og indtager hele Axekruinningens 

 Bredde (Fig. 5 a'), — og da Axens Spids, der ender paa 

 det Sted, hvor de tvende dorsale Septa smelte sammen, 

 er fæstet her, altsaa langt dybere nede end den høieste 

 Del af Krumningen, saa dannes en blindsækformig Udvid- 

 ning af hver Sidekanal derved, at de fra Axeskeden ud- 

 gaaende to ventrale Septa drages op over Krumningen 

 (Fig. 5 Sh"). Den ikke blindsækformige Del af Side- 

 kanalen fortsætter nu sit Løb opover den axeløse Del af 

 Rachis, hvor den kun maaler 2 Mm. i Gjennemsnit (Fig. 

 5 Sh'), indtil den 12 Mm. fra Spidsen ender haarformig. 



For end bedre at gjøre dette meget indviklede For- 

 hold mellem Åxen og Sidekanalerne forstaaeligt, have vi 

 leveret 3 schematiserede Gjennemsnit, hvortil vi henvise. 



Axen, der er forsynet med en Cuticula og en Skede, 

 nærmer sig opad mere og mere Ventralfladen, og bliver 

 alt tyndere og tyndere, indtil den i en Afstand af 62 Mm. 

 (største Exemplar) gjør en Bøining fra Ventral- mod Dor- 

 salfladen lidt skjevt til Høire, gaar saa atter nedad i en 

 Strækning af omtr. 20 Mm., hvorved dannes en stærk 

 Bue, hvis Bredde udgjør 10—12 Mm. Nu bøier den sig 

 atter mod Ventralfladen lidt til Venstre, hvor den paany 

 krummer sig for at gaa et lidet Stykke mod Dorsalfladen, 

 gjør her den sidste og mindste Bøining, førend den ender 

 tynd som en fin Synaalsspids paa det ovenfor omtalte Sted. 

 Paa denne Vei danner den ikke mindre end 4 Anser 

 (Fig. 7); paa mindre Exemplarer fandtes kun 3. — Nedad 

 i Stilken derimod bliver den alt tykkere og tykkere, er 

 temmelig knudret paa Overfladen, og danner ved den 

 opsvulmede, kjødede Del en Bue, hvis convexe Del svarer 

 til Dorsalfladen og den concave til Ventralfladen. Nu 

 løber den et lidet Stykke næsten perpendiculært, men 

 danner da atter en Bøining, hvis convexe Del vender til 



that neither he nor Kølliker had had opportunity to 

 make any thorough anatomical investigation. 



The vascular system in the Ptilella grandis differs 

 somewhat from that which, according to Kölliker's descrip- 

 tion, belongs to the Pennatulidæ in general. With respect 

 to the longitudinal canals, it is to be remarked that the 

 ventral canal is rather narrow; the lateral canals sur- 

 rounding the axis are each severally wider; and the dorsal 

 canal is at least as wide as both of them together. 



The dorsal canal goes right up to the point of the 

 Rachis; this is also the case with the ventral canal; but 

 the latter forms, at a distance of 100 Mm. from the point 

 a great enlargement (fig. 4, 5, v') in order to make room 

 for the bent axis (fig. 4 a). The enlargement is 30—40 

 Mm. long, and about 15 Mm. wide; while above and 

 below it the canal is only 6 Mm. wide. The lateral 

 canals (fig. 4, 5 Sv Sh) which surround the axis, extend 

 in their whole width up to that place where the ex- 

 tension of the ventral canal and the curvature of the 

 axis begin. As the axis bends itself, its sheath is stretched 

 so as to form a double membrane, which is tightly extended 

 and which occupies the whole width of the curvature 

 of the axis (fig. 5 a') and as the point of the axis, which 

 terminates at the place where the two dorsal septa 

 unite, is attached here, that is to say much lower down 

 than the highest part of the curvature, there is formed 

 a cæcum-like enlargement of each lateral canal, by the 

 two ventral septa, which proceed from the sheath of the 

 axis, being drawn up over the curvature (fig. 5 Sh"). 

 The part of the lateral canal which is not cæcum-like, 

 continues its course along that part of the Rachis which 

 is without axis: and it is here only 2 Mm. in diameter 

 (fig. 5 Sh') until it terminates in a capillary form about 

 12 Mm. from the point. 



The better to elucidate this very complicated rela- 

 tionship between the axis and the lateral canals, we have 

 given 3 schematised sections, on which we remark. 



The axis, which is furnished with a cuticle and a 

 sheath, approaches the ventral surface more and more in 

 an upward direction and becomes thinner and thinner, 

 until at a distance of 62 Mm. (in the largest specimens) 

 it makes a curve from the ventral towards the dorsal sur- 

 face a little obliquely to the right; it then goes down again 

 in the length af about 20 Mm. whereby a strong curve 

 is formed with a breadth of 10—12 Mm. It now curves 

 itself again towards the ventral surface a little to the 

 left, where it again turns a little way towards the dorsal 

 surface, makes here the last and smallest curve before 

 it terminates, as thin as the point of a fine needle, at 

 the place above mentioned. In this course it forms no 

 less than 4 curves (fig. 7) in small specimens there 

 are only 3. But below in the stalk it becomes on the 

 contrary thicker and thicker, it is rather tuberculous 

 on the surface, and forms with its enlarged fleshy part 

 a curve, the convex part of which answers to the dorsal 

 surface, and the concave part to the ventral surface; it 



Ml 



