Trachelomonas inconstans, a ?iew Flagellate. 119 
The whole case is strongly impregnated with iron, particularly 
in the older specimens, and this often gives the empty cases a 
slightly yellowish colour. The iron penetrates into the basal 
nodule, and even the tiny spicules attached to it, if these are 
present, show traces of iron. 
In the living condition the external surface of the case is 
apparently densely covered with very short spines, but examination 
with higher magnification, or after the use of various stains shows 
that this is not so. The appearance is due to the presence of 
minute pores within the thickness of the wall (Fig. 1,G). These 
pores are brought out particularly well after staining with 
haematoxylin, and also by the Prussian Blue test for iron. The 
general mass of the case, by virtue of its iron content, stains very 
deeply with either of these reagents, whilst the pores remain 
unstained and are clearly visible. In specimens having fairly thick 
cases these pores are particularly noticeable, and give the appear¬ 
ance of small spicules projecting from the surface 1 . 
In very old specimens the cases tend to break up into irregular 
angular plates (Fig. 1, E, F and H), losing their shape and collaps¬ 
ing slightly, although the plates still remain in contact with one 
another for some considerable time. 
The living cell is densely green in colour, and is provided with 
a bright red stigma whilst a long flagellum protrudes from the neck 
of the case. There are several contractile vacuoles (Fig. 1, I). 
Trachelomonas inconstans sp. n. Integumentum oviforme vel 
ellipticum, plerumque inferne aut interdum superne amplius, 
tuberculo basali fibuliformi vel conico, senio latiore ac irregulari 
prjeditum, ad collum magis incrassatum, provectiore aetate ferro 
valde coloratum, atque grosse punctatum ita ut prima specie 
spinulis curtis horrescens videatur, postremo in plagulas poiygonales 
dirumpendum. 
Long. 35-47 /m, Lat. 20-28 /m. 
Cellula viva saturate viridis, stigmate vivide rubro ac flagello 
instructa. 
Hab. in stagnis palustribus, Longmoor Pool, Sutton Park, 
Warwickshire. 
In conclusion, I wish to express my thanks to Professor G. S. 
West for much help during the investigation. 
Thb Botanical Laboratory, 
University of Birmingham. 
1 The typical form of T. hispida (Perty) Stem actually has its case covered 
with short spines. In a certain variety, however, var. coronata Lemm. which 
occurred in the same collection with the species under consideration, these 
spines are wanting, and the case shows a similar punctate structure. 
