12 FRIDTJOF NANSEN. [norw. pol. exp. 



"In the beginning of the observation the animal had the same regular 

 shape as the ordinary transparent and colourless form (PI. I, Figs. 3, 4 and 5). 

 The animal now began to swim about rapidly backwards in the open spaces 

 of water, continually rotating round its longitudinal axis the same direction 

 as the spiral-windings which are left-handed. The proboscis was stretched 

 far out, being dragged after, apparently in an inert state. Neither in this 

 nor in a later individual did I see the proboscis move while in this state. 

 The body was now gradually shortened and finally assumed a perfectly glo- 

 bular shape as in Fig. 6, a. Whilst this happened the proboscis disappeared 

 to same extent, and only a short protuberance (Fig. 6, a) remained. It seemed 

 to me as if the rest of it might have been dropped, but it may probably 

 have been contracted into the body. In certain positions of the animal, e. g. 

 in a lateral aspect when the proboscis and anal region were seen simul- 

 taneously, it looked as if the cilia were situated several together at certain 

 intervals (PI. II, Fig. 6, o). This was very often the case only on one side 

 of the animal (see Fig. 7, c, under side). I sometimes was able to count 9 

 such small tassels of cilia on one side between the anterior and posterior end. 

 In other positions of the animal, when it was seen more from one of the 

 ends, and had a perfectly round appearance (PI. II, Fig. 7, a) the cilia were 

 more uniformly distributed along the whole circumference of the body. I got 

 the impression that the cilia were chiefly situated along the furrows of the 

 spiral windings, e. g. in PI. II. Fig. 7, e there seemed even to be indications 

 of such small depression, in which the cilia were situated, along the under 

 margin of the animal. In the oral and anal region the cilia were more 

 densely distributed, and were also longer, especially in the oral region. 



"After a while the globe, (PI. II, Fig. 6, a) burst, and parts of the con- 

 tents were spread outside the membrane (Fig. 6, b). There were a great 

 number of rapidly oscillating, dark green grains, of exactly the same colour 

 as the cell contents. They seemed to be the cause of the dark colour of the 

 animal. By means of their oscillating movement these grains swam far away 

 in all directions 1 . After about half an hour they became mostly quiet, until 

 finally the whole mass seemed perfectly dead. The observation was made in 

 a drop of water, hanging under a cover-glass, in a microscope aquarium. The 



This oscillatory motion may probably liave been due simply to the surface tension. 



