834 SUMMAKY OF CURRENT RESEARCHES RELATING TO 



to wMch a trace of iodine-green has been added, is a good staining 

 reagent. 



Mounting Infusoria.* — Prof. C. W. Hargitt places some water con- 

 taining the animals (paramaecia, vorticella, hydroids) on a watch-glass, 

 and removes as much as possible with a pipette, and completes the 

 reduction by means of a thread siphon. The animals are next killed 

 v/ith a saturated solution of corrosive sublimate, Lang's fluid, which is 

 essentially the same as the foregoing plus a small quantity of acetic 

 acid, osmic acid, or picric acid. After killing, it is only necessary to 

 hardeu the protoplasm by the ordinary method of alcohol of increasing 

 strength, then to stain them, and afterwards mount in balsam. 



Transference from one medium to another is best effected by means 

 of the thread siphon. By this method the author has secured amcsb^ 

 naturally expanded, and exhibiting almost every phase of their life- 

 history. 



The final mounting may be done with equal success in glycerin or 

 glycerin-jelly. 



Medium for mounting Starches and PoUens.f— Mr. A. P. Brown 

 advticates the use of the following medium for starches, pollens, and 

 vegetable tissues : — Selected gum arable, 2 oz. ; glycerin and distilled 

 water, each 1^ oz. ; thymol, 1 gr. Put in a wide-mouthed well-corked 

 bottle, and place in a warm situation. Stir occasionally until perfectly 

 dissolved. Then strain through linen and set aside for about a week to 

 get rid of air-bubbles, or filter through a " hot filter." 



To mount starches or pollens a clean slide is breathed on and then 

 dusted over with the starch or pollen, excess of which is to be removed 

 by tapping the slide gently against the table. A drop of the mounting 

 medium is then placed en the slide and the cover-glass imposed. If any 

 air-bubbles are in the medium they must be picked out with the needle. 

 The cover-glass may be ringed round with cement directly. 



Preparing Diatoms. — Mr. C. Haughton Gill writes: — When cleaned 

 and dry diatoms are soaked in a concentrated solution of ferric chloride 

 (perchloride of iron) for some time all hollow spaces contained in the 

 frustules become charged with the iron salt. If they be now transferred 

 to an acid solution of potassium ferrocyanide, Prussian blue will be 

 formed both outside and inside all hollows and cavities. On washing 

 and levigating with water the outside unconfined portion of the precipi- 

 tate can be washed away in great part, while those portions which are 

 more or less surrounded by walls of silica remain in place, and serve to 

 clearly mark the position and limits of the spaces containing them. 



Evaporating a solution of sodium platinum chloride on cleansed 

 diatoms, and igniting the whole with addition of some crystals of oxalic 

 acid, serves to charge the minute cavities, to be described later, with 

 a deposit of s-pongy platinum. 



Pinnularise under either of these treatments show their coarse ribbing 

 to consist of ribbon-shaped tubes contained in the walls of the frustule. 

 Pleurosigma, Stauroneis, Cocconema, &c., show their " dots " to be 

 spaces which can be filled by foreign bodies. Coscinodisci have the 

 openings into their lacunae so large that the precipitates for the most 



• Amcr. Moil. Micr. Journ., x. (1889) pp. 183-4. 

 t Amcr. Journ. of PLarmaey, April 1889. 



