228 THE AMERICAN MONTHLY [Au 



for microscopy, for notes extracted from the Postal Mi- 

 croscopical Society's memoranda. It is hoped that these 

 will contain information a» interesting to our readers as 

 to the members of the Society, and will lead to profitable 

 discussion in our columns. Before closing this announce- 

 ment we desire to draw the attention of our readers, who 

 are workers in the field of microscopy, to the man}'' ad- 

 vantages accruing to membership of the Postal Micro- 

 scopical Society. Full particulars may be obtained from 

 the Honorary Secretary, Miss Florence Phillips, "Haford 

 Euryu," Colwyn Bay, North Wales. 



Method of Preserving and Mounting Rotifera. — 

 The following is Mr. Rousselet's method, communicated 

 to the Manchester Microscopical Society by Mr. Mark L. 

 Sykes, F. R. M. 8. : "Rotifera cannot be killed suddenly 

 by any known process without contracting violently and 

 losing all their natural appearance. To kill and preserve 

 them with their cilia fully expanded and in their natural 

 condition, the animals should first be narcotized with a 

 solution consisting of 2 per cent solution of hydrochlo- 

 rate of cocain, 3 parts ; methylated spirit, 1 part ; water, 

 6 parts. The rotifers should first be isolated in a watch- 

 glass and clean water, and a drop, or two drops, of the 

 solution added at first. After five or ten minutes another 

 drop should be added, and afterwards drop by drop and 

 very slowly, until the animals are completely narcotized. 

 They may then be killed and fixed by adding one drop of 

 a g- per cent to i per cent solution of osmic acid. To clear 

 from the solution they must be washed several times in 

 clean water, until all the acid is completely removed. The 

 rotifers must then be transferred to a 2i per cent solution 

 of formaldehyde (2J per cent of commercial, 60 per cent 

 formalin, and 37J per cent of distilled water), and should 

 be mounted in this fluid in hollow-ground glass slips. 

 The cells must be well secured after mounting by several 

 coats of cement. The process requires a little practice, 



