832 SUMMARY OF CUEEENT EESEAECHES RELATING TO 



Mounting Fish-scales.* — Mr. F. Dubois gives the following directions 

 for preparing and mounting fish-scales. Place the scales in a small 

 wide-necked bottle of caustic potash for forty-eight hours, then boil for 

 a few minutes in plain water and afterwards wash in hot water. Partially 

 dry the scales between blotters and place in alcohol for a quarter of an 

 hour to remove all moisture. The scales are then transferred to clove 

 oil for clearing. Now breathe on a clean cover-glass and apply side 

 breathed-on to a glass slip to which it will adhere. Place a small drop 

 of benzol balsam on the cover, put the scale on this, cover it with 

 another drop of balsam, and set aside for twenty-four hours. By the 

 following day the balsam will have become thick from evaporation of 

 the benzol. Now place a drop of fresh balsam on the slide, invert the 

 covei'-glass over it, and the mount is ready for ringing as soon as the 

 balsam is dry. Dry mounts should be made on cells, the scales having 

 previously undergone the same treatment. 



Preserving Marine Animals.f — M. M. Bedot preserves Siphono- 

 phora, &c., in the following manner : — A 15-20 per cent, solution of 

 sulphate of copper is made in distilled water. In this the colony to be 

 fixed is immersed. At the same time as the Siphonophora are plunged 

 in the copper solution sea- water is also poured in along with them, and 

 in such bulk that the copper solution is ten times as great. When the 

 animals are fixed (this happens in a few minutes) a few drops of nitric 

 acid are added to the solution and the mixture is gently stirred up with 

 a glass rod in order to prevent the formation of any precipitate. The 

 Siphonophora are left in the solution for four or five hours, and may 

 then be hardened. Hardening is best done with Flemming's mixture : — 

 1 per cent, chromic acid, 15 parts; 2 per cent, osmic acid, 4 parts; 

 glacial acetic acid, 1 part. In order to avoid touching the animal or 

 removing it from the vessel, the fluids should be changed by decanting. 

 The Flemming's mixture should be allowed to act for twenty-four hours 

 and should be twice the volume of the copper solution. 



The next operation, that of transferring the animal to alcohol, should 

 be done very gradually. A few drops of 25 per cent, spirit are first 

 mixed with the fluid by means of a pipette. Gradually the quantity 

 and strength of the spirit are to be increased, until in fifteen days 70 per 

 cent, spirit may be used. After this 90 per cent, spirit may be 

 employed. 



Examination of Protozoa.| — The technique to be observed in the 

 examination of the Protozoa, says Dr. Fabre-Domergue, is divisible into 

 three heads, the examination during life, fixation, staining, and mounting. 



In examining the animals while alive, should they be sufficiently 

 large as to be visible with the naked eye, then no cover-glass is 

 necessary, and by gradually diminishing the quantity of water, they are 

 at last rendered sufficiently motionless to be examined with facility. If 

 the animals be found too lively they should be left for some hours in 

 the warm chamber until they have settled down, and this they do usually 

 at a little distance from the edge either of the drop of water or of the 

 cover-glass. Certain colouring matters are very useful, especially 



* The Microscope, ix, (1889) pp. 184-5, fiom The Garner, May 1889. 



t Arch. Sci. Phj-s. et Nat., xxi. (1889) p. 556. 



X Aunales de Micrographie, ii. (1889) pp. 545-551. 



