Abstract
THE collar-cells are in normal life short and barrel-shaped, with separated cylindrical collars, which are never united. In certain pathological conditions, probably connected with suffocation, they elongate very greatly, diminishing in the diameter of their upper part, or "collum;" and in some species, though not in Sycon compressum, the collars may then come into contact. In certain other pathological conditions the collar is lost, though apparently it can be regenerated. These metamorphoses appear unconnected with the ingestion of food, which also was not found to induce any migration of the collar-cells. On the other hand, migration seemed to occur under exceptionally unhealthy conditions.
The collar is made up of (in Sycon compressum) about thirty parallel rods united by a film of some other substance. The flagellum is intimately connected with the nuclear membrane. There is an interstitial substance between the bodies of the cells. The area inside the collar appears to be provided with a sphincter membrane.
Cells preserved and cut by the paraffin method show an average contraction of 5:4 linear in the best sections. In most preparations this contraction is uneven, producing Sollas's membrane and other fictitious appearances.
Publisher
The Company of Biologists
Cited by
1 articles.
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