1 22 Bristol. — Life-history and Cytology of Chlorochytrium grande. 
sphaera , Borzi (1883), render it most improbable that they should be regarded 
as independent genera. Again, the resemblances between Scotino sphaera 
and Chlorochytrium are of so much more fundamental a character than the 
differences between them that it seems advisable to include all of these 
so-called ‘ genera * in a single genus Chlorochytrium. In this case the new 
species described in this paper will have to be named Chlorochytrium 
grande , not Centrosphaer a grande. 
Diagnosis. 
Chlorochytrium grande , sp. nov. Cellulae vegetativae sphaericae, 
subsphaericae, v. ellipsoideae, 6 5-75 \x diam., membrana sat aequali, chloro- 
phora singula magna superficie in lobulos plurimos producta, granulis 
amylaceis oleo pyrenoidibus numero ludentibus donatae. 
Propagatio fit divisione simultanea contentus cellularum in aplanosporas, 
vel interdum bipartitione repetita in zoogonidia agamica. Zoogonidangia 
130 ju- diam., membrana 6— 15 jut crass., paxillis instructa externis 1-2 e sub- 
stantia pectica constantibus atque internis uno v. pluribus saepissime maxi- 
mis et subinde intra plasma ramosis e cellulosa constantibus. Zoogonidia 
biciliata ovalia v. pyriformia, 3*5-5 ja long., 2 /x lat., cum vesicula evacuata. 
Hah. in limo fossae permagnae prope Doncaster, W. Yorks. 
A Note on the Genus Phyllobium , Klebs. 
The only other genus belonging to this group of algae is Phyllobium , 
Klebs (1881). This undoubtedly stands alone as an independent genus, not 
only on account of its life-history but also from its external appearance and 
its cytology. This genus is epiphytic, and the resting cells, which bear con- 
siderable external resemblance to those of Chlorochytrium , are attached 
at the base to a vegetative thallus, which in P. sphagnicola 1 consists of 
branching and anastomosing threads, which penetrate through the air-pores 
into the hyaline cells of the host. 
An examination has been made of the cytology of P. sphagnicola from 
material preserved in formalin and very kindly provided by Prof. G. S. 
West. The material was first washed for two or three days with successive 
relays of clean water in order to remove all traces of formalin. Sections 
were then cut and stained with Delafield’s haematoxylin, Heidenhain’s 
iron-alum-haematoxylin, and with acid fuchsin-iodine-green. Such sections 
show a granular cytoplasmic network in the meshes of which are embedded 
an extraordinarily large number of pyrenoids, each with a starch sheath 
(Text-fig. 2). On treatment with a dilute solution of iodine the starch 
sheaths assume a light blue colour, while the pyreno-crystal becomes deep 
brown. No large nucleus is present in the cell, but under a magnification 
°f 1,435 diameters a number of very small nuclei can be seen in the cyto- 
1 G. S. West : Some Critical Green Algae. Journ. Linn. Soc., Bot, vol. xxxviii, Jan. 1908. 
