188 Transactions of the Society. 



alcohol. The properties of sulphurous oxide are too well known 

 to require any comment. I will merely mention that it is soluble 

 to the extent of 30 volumes in 1 volume of cold water ; but 

 this solution soon changes into sulphuric acid by the action of air. 

 If, however, the gas is passed into alcohol the quantity absorbed is 

 greatly increased. If this saturated solution of the gas in alcohol 

 is added to water, the gas, or the greater portion of it, is instantly 

 thrown oflf. This alcoholic solution I have found most satisfactory 

 in the observation of Infusoria. "When a minute quantity is added 

 to a drop of water on a slip, there is at first the repellent action 

 between the alcohol and the water. This being overcome, the gas 

 is given off, and its effect upon infusorial life is at once apparent. 

 If the solution is strong, they are at once killed, and in most cases, 

 if the Infusoria are ciliate, the cilia are rendered visible ; but if the 

 solution has been strong enough to be hurtful but not deadly, 

 examination may be carried on very satisfactorily. The Infusoria 

 are rendered almost motionless, while the ciliary action may be well 

 observed. 



If, under these conditions, the slip containing Paramseeia is 

 allowed to become dry, the points of attachment of the cilia to the 

 body of the animal are exceedingly well defined. Where the cilia 

 have become detached, they almost resemble raphides. 



I think that this reagent — sulphurous oxide in alcohol — is one 

 that may prove of great use in microscopy. It is not so deadly as 

 osmic acid, but it has a very marked action on Infusoria ; while it is 

 by no means so dangerous, and its cost is much less. The solution 

 in water possesses very powerful bleaching properties, and the alco- 

 holic solution, which is perfectly stable, furnishes a ready means of 

 obtaining small quantities of sulphurous acid, for bleaching or 

 other purposes. 



I would merely add in conclusion that I consider I ought 

 almost to apologize for dealing with a subject so very foreign to my 

 usual microscopical pursuits. The experiments I have described 

 have been carried out more as a microscopical recreation than as 

 a scientific research ; but they have appeared to me, and to those 

 microscopists to whom I have shown them, to be of so much 

 interest, and so capable in the hands of those more conversant 

 wnth the subject than myself of further extension, that I have been 

 induced to bring them forward. 



