10 FRIDTJOF NANSEN. [norw. pol. EXP. 



On several occasions I believed I was able to make out that the eilia 

 on the surface of the body, were situated along the spirally wound furrows. 



Some individuals did not, however, show any indications of these spi- 

 rally wound furrows. This was, for instance, the case with the one, illu- 

 strated in Figs. 1 and 2. This specimen was on the whole very big and well 

 fed, "and it is possible that the furrows may have apparently disappeared, 

 owing to the abundance of food which had dilated the outer membrane. I 

 consider this explanation more feasible than that this was another species. 

 It behaved othervise in every respect, like the other specimens. 



The nucleus of the animal was situated in its central region, and was, 

 as seen in individuals killed with osmic acid, sometimes oblong (Figs. 6 — 8), 

 and sometimes extended into four branches (Figs. 4—5). 



A vacuole was very frequently seen in the posterior region (Figs. 4, 5, 

 14). It was sometimes divided into three smaller vacuoles (Fig. 10). 



The cell-contents were as a rule, at least in the outer layer, filled with 

 numerous globules (see Figs. 1 and 2), which were probably drops of oily 

 substance (nourishment) dispersed in the protoplasm. These globules were 

 more sharply defined by the effect of a very thin solution of osmic acid 

 (Fig. 9). After the specimens, having been stained, had been transferred to 

 Canada Balsam the globules had entirely disappeared ; they (Figs. 4—6) had 

 probably been dissolved. The oily globules were in the transparent speci- 

 mens colourless, or they might have a slightly greenish tinge. 



In the interior of specimens transferred to Canada Balsam, refractive 

 grains were often seen (Figs. 4 and 5). They were evidently mineral grains 

 or debris of diatom-shells, which had been taken in with the food. In Fig. 4 a 

 good many such grains are seen accumulated in the vacuole near the pos- 

 terior end. In Fig. 5 similar grains outside the individual are also seen 

 adhering to the cilia round the proboscis. 



When the animals were killed with osmic acid or chromo-aceto-osmic 

 acid, they sometimes retained more or less of their elongated shape (Figs. 

 4—7). But sometimes they contracted into a more or less spheroidal form 

 like Figs. 8 and 9, and the spirally wound furrows then often disappeared. 

 Fig. 9 was an individual which while alive, had the same appearance and 

 was in the same preparation as Fig. 3. 



