THE MICROSCOPE. 69 
phores. It possesses a large bright red globule remotely resembling 
the float. An accurate description of this taster is yet to be made, 
for its histological structure has never been determined. One is, 
however, tempted to regard it as in some way connected with the 
glands of Forskalia, which discharge their contents when the animal 
isalarmed. I have never, however, seen this so-called oil-globule lose 
its contents, even when the taster is broken from its connection with 
Nanomia. 
It seems not unreasonable to conclude that the discharge of a 
highly colored fluid by the scales of Agalma is in part a means of 
protection for the medusa, and it would seem natural to connect it 
with the function of excretion. We know so little about the charac- 
ter of the excretions, and the manner in which they are produced in 
Meduse, that at present we can hardly definitely ascribe the special 
function to these glands. Possibly similar glands are found in other 
Physophores, and the excretion has not been recognized from 
the fact that it is not so highly colored as in Agalma clausi and 
Forskalia. The discharge of this fluid from a living animal, if it 
take place without rupture of the wall of the scale, would imply 
special excretory openings somewhere on the bract. One is tempted 
to search for such openings, if they exist, on the distal tip of the 
scale, when they would be homologous to the excretory openings 
known to exist on the bell margin of certain Hydromedusz, as 
Metschnikoff and others have shown. 
Boston, Mass. 
CEMENTS, VARNISHES AND CELLS.* 
H, N. LYON, M. D. 
VERY one who continues in a given line of work for a number 
of years gradually confines himself to the use of a few agents. 
It is especially so in microscopy, and in these few remarks on 
cements, varnishes and cells, I shall mention only those that I have 
’ adopted, after having tried many and met with many failures. 
I have selected this subject because, to me, it is of great impor- 
tance, and while I may not add anything to the existing knowledge 
of the subject, my testimony may be of value in helping to settle 
that vexed question as to what makes the best cement, varnish, or 
cell. 
For some eight years I have been experimenting in this line 
and the experiment which finally settled the question, in my mind, 
* Read before the State Microscopical Societys, January 11th, 1889. 
