172 NOTES AND MEMORANDA. 



amphibia, and molluscs, for examining the circulation in the 

 transparent membranes of fishes, and for all other purposes 

 Avhen it is necessary that the object under examination 

 should be immersed in a considerable quantity of fluid. The 

 examination of vomited matters, neglected as a rule by 

 practitioners, will be, in some instances, also greatly facili- 

 tated by Dr. Dudgeon's submersion tube. 



Mr. Adie, of Pall Mall, or any other optirtan, can make a 

 submersion tube to fit on to an objective of any power up to 

 a quarter of an inch, and perhaps even to objectives of higher 

 powers, though, for ordinary purposes, it is not necessary to 

 go beyond the quarter-inch objective. It is scarcely 

 necessary to remove the submersion tube when examining 

 objects in the ordinary way between two plates of glass, for 

 the thin glass plate that closes the end of the tube does not 

 appreciably affect the distinctness of definition of the object 

 seen through it. The glass trough should be made of pieces 

 of plate glass cemented together with marine glue. For 

 examining urine it need not be more than two inches square 

 and one inch deep. We are of opinion, from a careful trial 

 with the submersion tube, that its advantages are such as to 

 encourage and simplify the use of the microscope in the 

 wards and in private practice. — Ibid. 



