36 Scientifie Proceedings, Royal Dublin Society. 
inch in diameter, and generally grouped in pairs or triplets. With 
them was one cell ;;5> inch diameter containing another half 
the size. On 19th December after four days exposure to west and 
north-west wind not exceeding force 3, I noted amongst the 
usual inorganic particles several cells of a unicellular Alga g¢o55 
inch diameter with transparent walls and brilliant crimson con- 
tents, the outer wall sometimes so thick that the contents looked 
likelittlemorethana crimson nucleus, sometimes, on the other hand, 
the red contents filled the whole sphere. With these were opaque 
cells of about the same size, setting free on rupture minute gra- 
nules, like those found in the slide of 13th December. In 
these observations, in order to avoid contamination from air on 
board ship, this microscope was used in a snow house on shore 
without further inconvenience than the slow destruction of its 
mercurial reflector. The contents of the air were afterwards more 
readily collected by exposing a clean glass plate to receive the 
precipitation of microscopic prisms of ice that fell abundantly even 
in the clearest weather. This device was adopted to observe the 
inorganic precipitate, described by me in a recent communication 
to the Royal Society. It had the opposite disadvantage to the 
Pouchet’s filter, because it could only be used in absolute calm, and 
it was not suited for the collection of organisms, because the 
melted ice dust, or anything else in the shape of water, could only 
be examined in the warmth on board the ship, where it was ex- 
posed to the risk of receiving and developing adventitious germs. 
To a contamination of this sort I attribute certain organisms found 
in alr precipitate melted, and examined in my cabin, namely, 
growing Torula, cells and groups of Bacterium lineola, setting free 
individuals moving by jerks in one direction only. ‘The precipi- 
tates collected on a glass plate, frequently, however, yielded forms 
unquestionably deposited from the air. These consisted of the 
crimson Alga, already mentioned, and tough cells from a phyco- 
chromaceous Alga, each cell of which was biscuit shaped 53,5 inch 
in diameter, and marked with a central scar or wrinkle, and faint 
concentric rings, giving it an appearance ofa starch grain. ‘These 
cells were subsequently found both in the ice and in sea water, 
tightly packed ina tough capsule. Upon two occasions I founds 
fravments of Diatomaceze in the air precipitate thus collected. 
Locking at the carcases of musk oxen still hanging in our rig 
