238 Prof. M'Intosli's Notes from the 



One of the latest contributions is a histological paper on 

 Owenia by Zurclieri*, avIio enters into the minute structnre 

 of the muscles, showing that the long spindle-shaped muscle- 

 cells have a spiral character (formerly noted by Ogneff), 

 ■which in transverse section give them a barred aspect. A 

 c'rcular muscular coat occurs only at the second dissepiment 

 and forward to the branchial lobes. Tliis also has spindle- 

 shaped cells with nuclei. He combats Gilson's view, as 

 Ogneff had previously done, that there is no line of demar- 

 cation between the muscular coat and the peritoneum, that 

 the nuclei arc rare in the muscular fibres and by-and-by 

 vanish, and that it is impossible to distinguish the nuclei of 

 the muscles and those of the gland-cells. He points out 

 that the peritoneal nuclei are generally rounded, whereas the 

 nuclei of the muscles are oval and flattened, with the long 

 axis in the line of the muscle-cell. He goes somewhat fully 

 into the histology of the circulatory system (his hsemocoel), 

 the main trunk consisting of a dorsal vessel carrying the 

 blood forward and a ventral trunk carrying it backward. 

 The dorsalforms a blood-sinus round the gut to the second 

 septum, then breaks up into a network over the canal, the 

 trunks fusing at the first septum and sending forward a 

 scries of vessels to the branchiae, the returning vessels 

 uniting to form the veiitral trunk helow the gut. The walls 

 of the vessels have a fine epithelial coat and a delicate circular 

 muscular layer with minute nuclei in tiieir s|)indle-shaped 

 cell--. The author also objects to Gilson's statement that 

 no special constrictor to the alimentary canal occurs at the 

 septa, and points out that at the third septum an efficient 

 constrictor aj)|)aratus exists both for the canal and the blood- 

 sinus, the muscular apparatus showing the large mnsele-cells 

 at the outer ends of the fibres. Posteriorly also the 

 alimentary canal is moniliform from its constrictions. He 

 is inclined to think that Drasche's bladder-like tissue on the 

 ventral mesentery is part of the reproductive apparatus. 

 The ampullae on the ventral blood-vessel, which Drasche 

 observed to be rythmically contractile, are confined to the 

 genital region of the body, and bear the reproductive 

 elements on their outer surfaces, and, though they have 

 muscular M'alls, Ziircher would attach more importance to 

 their nutritive capacity. The red blood contains rounded 

 or lenticular corpuscles with nuclei, and some corpuscles 

 undergo mitosis. He found them in the ampuUte and less 



* Jeuaisclie Zeitsclir, fiir Nalui'wi,<5:. 13cl..\lv. pp. 181-2^0. pis, xv.-xx. 

 (1009,). 



