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PROGRESS OF MICROSCOPICAL SCIENCE. 
poison was added. At first the ciliary motion seemed increased, but 
in about two minutes it became slower, and in six had become very- 
languid, and in ten minutes stopped altogether in the specimens of 
Paramoecium, but still continued in some of the cilia of the mantle. 
A little dilute cobra-poison was added to a piece of the mantle of a 
fresh-water mussel. The cilia began immediately to move much more 
rapidly. This was watched for some time. Ciliary motion not 
affected, or at all events not arrested, after more than half an hour. 
December 10. — A piece of the gills of a fresh- water mussel 
placed under the microscope and a little cobra-poison added at 
10.40 P.M. The cilia were extremely active. At 10.55 still active. 
11.5. Several ciliated amoeboid masses are now quiet instead of roll- 
ing over and over as they did, but the cilia on their surface are still 
moving. 11.15. The cilia on these Infusoria have now nearly all 
stopped. A few are moving slowly, whilst those on the gills are but 
little affected. 11.55. Cilia on the gills are still quite active. Those 
on the ciliated bodies still moving, rather more actively than before. 
1.30. Cilia on gills have become much more sharply outlined. Many 
are standing still, though many still move briskly. To another 
specimen a strong solution of cobra-poison was added at 10.50. 
1.30. Cilia still moving. A third specimen was laid in an almost 
syrupy solution of dried cobra-poison at 11.28. At 11.40 no effect 
observable. 1.30. Some have stopped, but numbers are still moving 
quite briskly. In fliis case the poison seemed not to have any action 
on the ciliary motion. 
January 6, 1875. — At 3.40 some diluted cobra-poison added to 
Vallisneria. Circulation going on vigorously. About -^^ grain in three 
drops of water. 3.58. The movements are unchanged. 5 p.m. Move- 
ments going on as before. Added some solution of cobra-poison 
at 4 P.M. to another specimen of Vallisneria. 4.10. No change. 
4.45. Circulation goes on vigorously. 4.55. Perhaps rather less brisk 
in their movements. 
The results of these experiments show that cobra-virus must be 
regarded as, to a certain extent, a poison to protoplasm, seeing that it 
arrested with rapidity the movements in Infusoria. Still it cannot be 
regarded certainly as a very powerful one, for the cilia of the fresh- 
water mussel continued to move for many hours in a strong solution 
of cobra-poison ; though in other experiments the action was appa- 
rently arrested even in weaker solutions of the poison. In the case 
of cilia from the frog's mouth, the results were more definite, but 
action was not invariably destroyed. The results of the action of the 
poison on the amoeboid movements of the blood-corpuscles are not 
very definite. In the case of Vallisneria, the circulation in the cells 
went on with undiminished vigour after the application of the poison 
for two hours. 
Development of Teeth in Mammals, Birds, and Fishes. — -Mr. C. S. 
Tomes, M.A., has contributed a valuable paper to the Eoyal Society,* 
of which the following is a very brief abstract. He says : " Observa- 
* ' Proceedings of the Koyal Society,' No. 160. 
