NO. 16.] PROT OZOA ON THE ICE-FLOES OF THE NORTH POLAR SEA. 13 



bursting of the cell could not therefore be due to pressure of the cover-glass, 

 as I had thought possible on other previous occasions. Neither was dessica- 

 tion the cause, for as far as I could see there was plenty of water in the 

 drop. But something may probably have been wrong with the water, because 

 another infusorium that lived in the same drop, also seemed to die after a 

 while." 



"PI. If, Figs. 7, a, b, c, and d, are drawings of another individual of the 

 same kind, which I observed under the microscope for 12 hours, on July 28, 

 1894. Fig. 7, a was drawn at noon, and the last drawing, Fig. 7, d, was 

 made at midnight on the same day. The animal was living all the time, 

 and the cilia were in rapid motion, especially during the first six hours. The 

 long cilia round the proboscis were especially active, and were bent far towards 

 all sides. After 9 hours (Fig. 7, c), the cilia were still in constant motion in 

 the anal region, but perfectly quiet in the anterior portion of the animal. The 

 proboscis had now almost entirely disappeared, only a small protuberance 

 being left. After 11 hours no cilia moved. The form of the animal was 

 during the first six hours almost perfectly globular, even in a lateral aspect 

 (see Fig. 7, 6). It became then more oblong, like a short egg (Fig. 7, c), thus 

 it remained for four hours (Fig. 7, d); but then (after eleven hours) it again 

 became perfectly globular. 



"In the anal region at the posterior end, a colourless, limpid space often 

 occurs (Figs. 7, b, c, d); which is sometimes larger sometimes smaller, but 

 always with the same locality in the anal region, where the latter is slightly 

 pointed. Small dark grains frequently occur inside this clear space, and are 

 seen to move. They sometimes pass from the dark cell-contents into the 

 limpid space approaching the cell-membrane. A little later the limpid space 

 is suddently and entirely closed by the dark mass; which after a while begins 

 to withdraw slowly from the membrane, to give room for the limpid space 

 again. While this is going on the cilia outside are in active motion 1 . 



1 On one such occasion I saw a spore-like body come out from these moving cilia, and 

 it appeared to have come through the anal opening, but might nevertheless have come 

 from the surrounding water. It had an oblong form, narrow in the middle like an 

 hourglass or the figure eight ; of yellowish colour, it was extremely small, and hardly 

 visible with the magnification used (Zeiss CC and 5). It had a rapid oscillating motion; 

 it moved about for a while, and then became quiet. Several similar corpuscles were 

 seen in the neighbourhood. Half an hour later a perfectly similar corpuscle came out 

 from the cilia. 



