172 TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGOW. 
Bonnemaisonia asparagoides, C. Ag., that gave a blue 
stain to paper. 
By Davin Rosertsoy, F.L.S., F.G.S.: 
[Read 26th December, 1894. ] 
A SPECIMEN of this alga was mounted in the usual way, on paper, 
in sea water. Nothing was noticed unusual about it till it was 
taken out of the press a day after, still in a damp state. It was 
then noticed that it had stained the paper a dark blue. It was 
supposed that it had become stained with ink, as the colour was 
much like that with which I had been writing. On closer exam- 
ination, it was seen that the colour had issued from along the 
branches only, and must have come from the connecting points 
of the plant and the paper. Another specimen of the same alga 
was tried ina similar way, with a like result. Other red sea- 
weeds, mounted by the same process, and on the same paper, 
were not affected in this manner. Again, another piece of 
Bonnemaisonia was mounted on a similar, though a different, 
paper, but in this no change took place. I was curious to know 
if this was common to the alga. Accordingly I sent a stained piece 
to Mr. George Murray, F.L.8., of the British Museum, who 
handed it over to Mr. A. Batters, F.L.S., an eminent Marine 
Botanist, who writes me—‘‘I have been examining the specimen 
of Bonnemaisonia on the stained paper that you sent to the British 
Museum. When a thin slice of the paper is examined under the’ 
microscope, the stain is seen to be made up of a number of minute 
bluish-violet grains, the colour being precisely that of starch 
stained by iodine. I am inclined to think there has been an 
excess of starch in the dressing of the paper, and that it has been 
acted on by the iodine contained in the alga.” He adds—* In 
ordinary cases Bonnemaisonia does not act in this manner.” 
What Mr. Batters suggests is most likely, in a great measure, to 
be correct—namely, that the blue stains most probably arise from 
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