Plate VI. 



Fig. I. Part of vertical lateral section (in the transversal plane), showing the relative position of the 

 testes and ovaries. On the outer subtentacular genital organ is seen the ectodermic invag- 

 ination; below the same is seen part of the tentacle-basis. The thick, dark lining to the right 

 of the figure is the epithelium of the "chimney"-cavity. 3°/i- 



— 2. Part of ^•ertical, median section (in the transversal plane), showing the oesophagus, the 



apical organ, the transverse canal and the root of the tentacle, above which lies the inner 

 part of the outer genital organ. Below are seen the stomodseal folds. The infundibulum can 

 scarcely be said to exist here. (Comp. Fig. 9). The left transverse canal wrongly designated 

 tr. instead of tr. c. "/j. 



— 3. Part of horizontal section, showing the two outer, subtentacular genital organs and the 



"chimney". In the ovary of the left genital organ is seen an egg in formation, enclosed b>- 

 its follicle. In the cavity of the organs are lying spermatozoa, especially in that to the left. 

 In the right genital organ the cavity within the o-Cary is an abnormal formation, probably 

 produced by the preservation. 3°/i. 



— 4. Section through a genital organ (right subsagittal); from a vertical section in the transversal 



plane. At its upper side is seen part of the ectodermal invagination. In the lumen of 

 the genital organ lies a small cluster of spermatozoa; in the ovary one egg is seen in for- 

 mation. s°/i. 



— 5. Part of the testis from a vertical section along the transversal plane. To the right are seen 



the young sexual cells, passing without limit into the (entodermal) epithelial lining of the 

 genital cavity. Towards the left of the figure the cells are seen to form the characteristic 

 packets of spermatogonia. The outermost packets to the left consist of nearly ripe sper- 

 matozoa. The epithelial lining of the testis towards the genital cavity is more or less vacuol- 

 ated. The position of this figure is not correct; the point ought to have been looking down- 

 wards. ^°°/i . 



— 6. Part of the ovar)-, from the same section, and same genital organ, from which fig. 5 is drawn. 



At the lower end the germinal zone is seen to pass without limit into the entodermal epithel- 

 ium lining the genital cavity. The large nuclei in the upper part of the figure indicate that 

 these cells are about to develop into eggs. 2°°/, . 



— 7. Horizontal section through the tentacle basis, showing the root of the tentacle and the collo- 



blast-layer covering both tentacle and the tentacular vessels; further the entodermal lining 

 of the tentacular vessels, having the same character as that of the genital organs. 4°/i. 



— 8. Part of vertical, nearly median section, j^arallel to the transversal plane, showing the direct 



continuation of the "suboral" cavity (f.) into the lumen of the "chimney". In the right 

 (subsagittal) genital organ the cavity is seen to be in connection with a branch from the 

 transverse canal, ^^/i . 



— g. Part of vertical median section, parallel to the transversal plane. The tentacle is seen in 



longitudinal section (combined from 2 — 3 successive sections). The main transverse canals are 

 seen in connection witli the oesophagus; infundibulum rudimentary. A secondary tentacle 

 is seen below the large, normal tentacle. 3°/,. 



