424 Griffiths.—On Glaucocystis Nostochinearum , Itzigsohn. 
inches deep and about twenty square yards in area. The soil was a red 
marl. A dense vegetation of Juncus communis, Alisma Plantago , and 
Ranunculus aquatilis nearly filled the pool. The occurrence of Glaucocystis 
in other than a Sphagnum- bog is not by any means a usual thing. No 
Sphagnum is found in the immediate district. 
Collection and Fixation. 
Tufts of the Fontinalis were pulled up and the water was squeezed out 
into glass tubes. Subsequently the sediment, consisting of decayed vegetable 
matter, filamentous Cyanophyceae, a few Desmids, Bacillarieae, and Glauco- 
cystis, was fixed either in a per cent, solution of formic aldehyde, 
or in a mixture of three parts absolute alcohol and one part glacial acetic 
acid. One drop of sediment contained under favourable conditions as many 
as twenty specimens of Glaucocystis. It was not found possible to separate 
the organisms from the flocculent matter in which they were found. In 
order to facilitate the treatment of the sediment in the alcohols and staining 
reagents, a centrifuge was used to bring the material down quickly to 
the bottom of the tube. 
Staining Reagents. 
For staining the chromoplast, safranin and fuchsin were found to 
be the best. For the structure of the nucleus, haematoxylin and gentian 
violet were most successful. Iron alum and haematoxylin proved fairly 
satisfactory also. In all cases the sediment was taken up through the 
alcohols into xylol, and mounted finally in Canada Balsam for examination. 
The Cell-Wall. 
The cell-wall of Glaucocystis strikingly resembles that of Oocystis. 
The cell is ellipsoidal in shape and has apical thickenings on the inner side 
of the cell-wall. In addition, however, there is an equatorial thickening on 
the outer side of the cell-wall. The wall is fairly thick, but when in the 
mother-cell condition it becomes very thin and ultimately ruptures. When 
treated with iodine in potassium iodide and strong sulphuric acid the 
cell-wall turns blue. It consists, therefore, very largely of cellulose. In 
this respect the cell-wall of Glaucocystis differs from that of most Cyano¬ 
phyceae. 
The Chromatophores. 
These are of very remarkable form. Hieronymus (’ 92 ) describes and 
figures a series of radiating, strongly curved chromatophores from twelve to 
twenty in number, and of a blue-green colour. When the cell is about 
to divide, these chromatophores break up into a large number of oval 
plastids. After cell-division the chromatophores are re-formed, I made 
