1896-97.] Mr George Murray on Marine, Diatoms. 
217 
same stage of development, not however so regularly in diatoms as 
in the cells of a filamentous Alga, the remarkable chain represented 
in fig. 1 shows three successive stages in three adjoining cells. 
The uppermost cell has undergone the first (transverse) division. 
In the second cell the contents are divided into four portions, and 
in the lowest cell each of these is rounded off. I have witnessed the 
processes of division up to four many times in the living Chcetoceros, 
but never the actual process of further subdivision. In fig. 2 there 
are represented two cells, one with eight, the other with sixteen 
completely rounded-off portions, and such variation of number in 
adjoining cells is not uncommon. As said above, I never had the 
good fortune to witness the subdivisions into eight and sixteen in 
the living cells, and it was only on searching the preserved material 
in London that instances came to light. In Ch. curvisetus (fig. 5) 
subdivisions into four and eight are shown also in adjoining 
cells. 
That these spore-like cells of Chcetoceros are destined to reproduce 
the parent form no one can doubt. But how ? Do they form 
Chcetoceros filaments by simple vegetative growth, each first secret- 
ing a membrane, siliceous or not, like the so-called “cysts” of 
Biddulphia — or like the eight and sixteen subdivided and rounded- 
off portions of the Coscinodiscus cell? In the absence of trust- 
worthy evidence the inevitable comparison with Coscinodiscus 
appears to furnish the most likely interpretation. 
That five weeks’ work at sea should have been rewarded with such 
unlooked for results — results which no one could have anticipated 
from the known facts about diatoms — I explain by the fact that 
botanists have hitherto confined their marine studies almost 
exclusively to shore plants. The instances of a botanist using a 
tow-net are few indeed, and I can only hope they will be more 
numerous in the future. The plant plankton of our coasts is 
exceedingly rich in minute Algae other than diatoms, the life- 
histories of which are imperfectly known. 
There is one object occasionally met with in the fine silk tow-net 
in autumn in the lochs of Western Scotland which I may be 
permitted to mention. In the Sound of Islay and again in Loch 
Hourn (though to a less extent) the adjoining hills were covered 
with heather in bloom, and I repeatedly captured quantities of 
