THE 
HEW PHYTOhOGIST. 
Vol. XIV, Nos. 6 & 7. June & July, 1915. 
[Published August 4th, 1915]. 
PLEODORINA ILLINOIENSIS * 1 KOFOID IN BRITAIN. 
By W. B. Grove, M.A. 
[With Eleven Figures in the Text]. 
HOWARDS the end of March, 1915, I made a very large 
1 gathering of this species, from cart-ruts in a ploughed field at 
Harborne, near Birmingham ; the water was covered at the time 
by a coat of ice. The gathering was almost pure, only a Pandorina 
or two and a few Flagellates being mixed with the predominant 
species. This, as will be seen later, is an unusual circumstance ; 
Pleodorina has been almost always found accompanied by Eudorina 
but none of the latter occurred in the Harborne material until 
nearly the end of April, when a small number began to be found in 
the field. When brought home, the gathering was preserved, and 
flourished in a basin in a cool room for more than seven weelis ; at 
the same time the species increased enormously in its original 
habitat and was kept under observation till the ruts dried up 
towards the end of May; during the latter part of the time a 
number of Rotifers and Anthophysa vegetans, etc., made their 
appearance as well as the Eudorina. 
All the colonies of the Pleodorina, without exception, were 
ellipsoidal in shape (Fig. 1), the diameters being occasionally in the 
ratio of as much as 10:7, though more usually about 9:7 and, 
although many individuals had the diameters more nearly approach¬ 
ing equality (as near as 6:5), none were seen that appeared circular, 
out of the immense number examined, except of course in end view. 
Observation soon showed that these colonies possessed a very 
marked polarity, always advancing in the direction of the longer 
axis, with one particular end foremost, rotating at the same time 
about that axis so that, when viewed from the anterior end, the 
1 Kofoid wrote “ illinoisensis ” which is repugnant to the Latin method. 
The law of priority does not concern itself with grammatical errors. 
