22 PRACTICAL HISTOLOGY. 



or watch-glass shaped, are in constant requisition, 

 since very many of the manipulations require to be 

 performed whilst the tissue is immersed and floated 

 out in fluid; while for applying reagents to a speci- 

 men under the microscope small pipettes are ex- 

 tremely convenient. 



Reagents. Two or three small bottles containing 

 the fluids which are most used for preserving and 

 mounting preparations should be always on the 

 work-table. Small bottles provided with a cap and 

 with a piece of glass tube drawn out to a point and 

 standing in the bottle are perhaps the best, but small 

 corked phials with a piece of glass tube passed 

 through the cork will answer every purpose. One 

 of these should contain a mixture of glycerine and 

 water (equal parts of each); another a solution of 

 Canada balsam in chloroform for fixing the cover- 

 glass when preparations have been mounted in gly- 

 cerine (this should have a small brush instead of a 

 glass tube) ; and another, which will not be used much 

 at first but will afterwards be often in requisition, 

 should contain dammar varnish. It is useful also to 

 have a wash-bottle of distilled water, a flask of salt 

 solution, a solution of chloride of sodium, containing 

 1 part of the salt to 150 or 200 of water, and a small 

 flask of recently prepared logwood alum stain ing- 

 solution. This is made by taking 5 grammes each 

 of powdered alum and extract of logwood, and rub- 

 bing them up thoroughly together in a mortar with 

 100 cc. of water. The mixture is covered and allowed 

 to stand overnight, it is then filtered into a bottle, 

 and a lew drops of a solution of peroxide of hydrogen 

 are added. The solution will keep two or three weeks 

 in good condition for staining, but it must always 

 be refiltered immediately before being used. 



Pipettes may be readily made by drawing out in 

 the flame a piece of soft glass tube at two places 

 close to one another, so that the intermediate part 

 remains as the bulb of the pipette. It is well to 

 make a number at a time, sealing up the ends in the 



