84. PROFESSOR RAY LANKESTER. 
at Le Croisic, on the coast of Britanny, bottles containing a 
quantity of the blue-green flocculent growth caused by 
Navicula ostrearia. The material was in the living con- 
dition, and when a drop was examined on the field of the 
microscope it was found to consist chiefly of an immense abun- 
dance of a remarkable blue-coloured Navicula (the N. ostre- 
aria), associated with a variety of other Diatomacee of the 
usual yellow-brown colour. The gatherings were obtained 
from tanks or “ saltings” on the flat coast in the neighbour- 
hood of Le Croisic. The Navicula ostrearia exhibited the 
usual to-and-fro gliding movements familiar to observers of 
living Diatomacez. 
The distinctive and remarkable feature about them was the 
presence of bright blue pigment, which appeared to be in some 
cases uniformly diffused through the cell-protoplasm, and in 
other cases to be confined to the two ends of the elongated 
cell-body (see figs. 1 to 9). 
It is to be noted that Gaillon described these Naviculez as 
uniformly impregnated with a green tint. It is hardly 
doubtful that this impression was due to the imperfect optical 
properties of Gaillon’s microscope. The Navicule are very 
minute, being only the ;},th of an inch in length and the 
7ziyoth of an inch at their greatest breadth, so that an inferior 
microscope might well be inadequate to enable an observer to 
distinguish the yellow-brown endochrome from the associated 
blue-coloured protoplasm, and might give a confused green 
appearance as the result of the combination of the two. 
The yellow-brown endochrome (c in the figures) of Navicula 
ostrearia is like that of other Diatoms, and calls for no special 
remark. It exists generally in the form of two broad bands; 
which may become twisted or broken in certain conditions of 
nutrition and osmotic action (see figures). 
The rest of the siliceous capsule is occupied by the cell- 
protoplasm (d), nucleus (a), and vacuoles (9). 
1 Tt will be found convenient to apply to this pigment a distinct name. I 
propose to call it ‘‘ Marennin,” in reference to the locality which has become 
celebrated through it. 
