90 
West and Griffiths . — The Lime- Sulphur Bacteria 
remainder of the protoplasm. The protoplast contains phosphorus, and 
the nucleo-protein is diffused throughout the reticulum in small granules. 
These granules are probably a form of chromatin which has but small 
affinity for nuclear stains. 
Known localities in British 
Isles . 1 
Habitat. 
H. mirabilis , West 
and Griffiths, 1909. 
H. palustris , sp. n. 
Length 42-86 jx. 
Breadth 20-33 A** 
Stanklin Pool, Worcs. 
Gt. Barr Park, Staffs. 
Studley, Warwickshire. 
King’s Norton, Warwickshire. 
Near Belfast, Ireland. 
Near Edinburgh, Scotland. 
In all cases 
in the mud of 
a freshwater 
pool. 
From | to § the size 
of II. mirabilis. 
Length 14-36^. 
Breadth 11-5-18 \i. 
During division the 
halves of the cell are 
much more rounded 
and the constriction 
more open. 
Near Dewsbury, W. Yorks. In Sphag- 
Near Bowness, Westmorland. num bogs. 
Cannock Chase, Staffs. 
Fair Head, Antrim, Ireland. 
Clare Island and near West- 
port, Mayo, Ireland. 
A point of considerable interest is the comparison of the results 
obtained by the wet-staining and the dry-staining methods. It is possible 
to obtain a correct idea of the cytological structure only by never allowing 
the organisms to become dry. Dry-stained specimens all show some kind 
of concentration of the protoplast, of very variable form, which is purely an 
artifact. Drawings of such specimens reduced by photography to a size 
approximately the same as those usually published of much smaller 
Bacteria show apparent nuclear masses very similar to those asserted to be 
found in the smaller species. In the case of Hillhousia these * nuclear * 
masses are certainly artifacts due to the superposition of the protoplasmic 
threads on drying. 
It is possible that similar effects may be produced when smaller 
Bacteria are prepared by the dry-staining method, and consequently some 
doubt must be thrown on any conclusions regarding the cytology of 
specimens prepared in that way. 
DESCRIPTION OF PLATE IX. 
Illustrating the paper by Professor West and Mr. Griffiths on the genus Hillhousia. 
Fig. i. Normal aspect of living specimen of Hillhousia mirabilis. x 500. The dark globules 
consist of calcium carbonate. 
Fig. 2. Individual from which the calcium carbonate has been removed by dilute acetic acid. 
X 850. The protoplasmic reticulum is somewhat swollen and distorted, and the conspicuous 
granules are minute grains of sulphur. 
1 We have also observed H. palustris in material collected by Professor H. H. W. Pearson 
from the sides of a spring at Henkriesfontein, in Little Namaqualand, S. Africa. 
