DISCOVERY OF VOLVOX 259 
eight inches long, and of the thickness of the quill of a 
hen’s feather." One end (A) I left open, the other end (B) 
I plugged with a bit of cork (so that betwixt D and B 
there was nothing but air), with the idea that” when I 
came to handle the tube, the water wouldn’t run out of it. 
The air being now shut up in the tube, between D and B, 
cannot remain of the same volume, or extent, but changes 
at every moment, so to speak; for one can’t approach the 
tube with the hand, the breath, or any part of the body 
that is a little warmer than the air wherein the tube is 
lying, without the air in the tube being affected by some 
part of it; and this warmth brings about an expansion 
or greater enlargement of the air (in the tube), whereby 
the water is made to move, being driven from DC towards 
A: notwithstanding we may perceive no motion in it 
with our naked eye. And just as the least warmth 
causes this outward displacement of the air in the glass 
tube, so likewise warmth readily departs from the tube, 
whereupon a movement of the water takes place* back 
from C towards B. 
In this water were included two of the foresaid round 
bodies,’ and these of the biggest sort; and contained in 
each of them were five little round particles,? which 
inclosed particles were pretty well grown in size: and in 
a third big body there lay seven round lesser particles. 
These last were uncommon small. 
After the lapse of four days, the said round bodies 
remaining shut up in the glass tube all this while, I 
perceived that in two of them the outermost membrane 
1 een schagt van een hoender [MS. honder] penne Dutch edition “of a 
Goose Quill” Phil. Trans. 
2 dat is here accidentally omitted in the MS., but restored in the printed 
version. 
3 
aan neemt MS. is nemende printed version. 
* j.e., mother-colonies. 
° i.e., daughter-colonies. 
