286 CORRESPONDENCE. 



through the objective, the angle of the emergent pencil was also easily 

 measured at the cylindrical surface. 



Cancelling so many reflecting surfaces of course increased the 

 volume of the illumination considerably. 



Respectfully yours, 



BoBERT B. TOLLES. 



Desiccation of Rotifers. 



To the Editor of the ' Monthly Microscopicul Journal? 



Sir, — I have read the article by Mr. H. Davis in the May number 

 of the ' Journal,' describing a new rotifer, and demonstrating by an 

 elaborate series of experiments, the mode by which a rotifer left high 

 and dry, is enabled to resist the desiccating influence of the atmo- 

 sphere. 



To my mind his discovery of the gelatinous envelope fully ex- 

 plains the phenomenon, and his experiments showing that this enve- 

 lope, after a prolonged exposure to powerful desiccating agencies, 

 still contains animal matter in a fluid state, finally disposes of a 

 question which has been a fruitful source of controversy for many a 

 long year. 



Continuing to turn over the leaves of the ' Journal,' in the happy 

 frame of mind induced by the feeling that in future it might be pos- 

 sible to take up a scientific publication without the dread of finding 

 in every page an allusion to the inevitable dried rotifer, I was sur- 

 prised to find a letter from Mr. Slack stating that Mr. Davis's dis- 

 coveries were so far from being novel, that the question had been 

 settled long ago. 



Now, as I look over most of the periodicals devoted to microscopy, 

 I began to think that, like a rotifer, I had just been revived after 

 lying dormant for years, so I turned to Mr. Slack's quotations, with 

 the determination of beginning at once to make up for lost time. 

 But what do I find? The quotations resemble Mr. Davis's paper, 

 only in the fact that they have to do with rotifers. In no one of them 

 can I find the slightest allusion to the means by which a rotifer, out 

 of its element, manages to preserve its moisture and consequently its 

 vitality. 



It should not be overlooked that the quotation from Dr. Pennetier 

 (perhaps the greatest authority cited by Mr. Slack) is, in sum and 

 substance, the very same as the quotation from the ' Cornhill Magazine,' 

 given by Mr. Davis himself in his paper. 



Whilst fully admitting the importance of carefully investigating 

 every statement which is advanced as a scientific fact, yet I cannot 

 help thinking that, in the present instance, an undeserved slur has 

 been cast upon the result of what appears to have been a long and 

 successful investigation. 



I am, Sir, yours faithfully, 



F. W. MlLLETT. 



