230 



THE AMEKICAN MONTHLY 



[December, 



tion of some favorite specimen from 

 the running in of the cementing 

 substance, or the running out of the 

 glycerin. 



It was in the winter of 1878-79 

 that my attention was first called to 

 a substance known in the Pathologi- 

 cal Laboratory, at Vienna, as Vene- 

 discher Damarlack (Venetian damar 

 varnish), which was exclusively used 

 for sealing and finishing glycerin- 

 mounts. On my return home I found 

 that no such substance was known to 

 the trade. After experimenting with 

 various articles I have found that 

 Venice turpentine, prepared as pre- 

 sently to be described, if not identical 

 with, it at least answers every purpose 

 equally as well as that known in 

 Vienna under the name of Venetian 

 damar varnish. Mr. Hopp, of this city, 

 who has conducted the experiments, 

 kindly furnishes the following direc- 

 tions for preparing the turpentine. 



Dissolve true Venice turpentine in 

 enough alcohol, so that after solution 

 it will pass readily through a filter, and, 

 after filtering, place in an evaporating 

 dish, and by means of a sand-bath 

 evaporate down to about three quar- 

 ters of the quantity originally used. 

 The best way to tell when the evapora- 

 tion has gone far enough, is to drop 

 some of the melted turpentine, after it 

 is evaporated down to about three 

 quarters its original volume, into cold 

 water, and in being taken out of the 

 water if it is hard, and breaks with a 

 vitreous fracture on being struck with 

 the point of a knife, cease evapora- 

 tion and allow to cool.* 



The following hints for applying 

 the turpentine may be found useful. 

 Square covers should be used. The 

 cover-glass being adjusted with the 

 usual precautions observed in glycerin 

 mounting, the surplus glycerin, if any, 

 should be wiped away, and the slide 

 so placed that the edges of the cover- 

 glass are plainly seen. 



A piece of wire No. 10-12 (copper 



* The prepared turpentine is kept on hand 

 by Mr. A. Maxwell, pharmacist, Cleveland, 

 O., who will fill all orders. 



is the best, as it gives to the turpen- 

 tine a beautiful greenish tinge) is 

 bent at right angles, the short arm 

 being just the length of the cover- 

 glass used. 



The wire is heated in the flame of 

 an alcohol lamp, and plunged into 

 the prepared turpentine, some of 

 which adheres to the wire. The wire 

 is then brought down flat upon the 

 slide at the margin of the cover, and 

 the turpentine will distribute itself 

 evenly along the entire side of the 

 cover. The same process is to be 

 carried out on each of the other three 

 sides. Any little unevenness may be 

 removed by passing over it with the 

 heated wire. The advantages of this 

 substance, over all others used for a 

 similar purpose, are : — 



It is secure. I have such thick 

 objects as the female organs of Ver- 

 micularis and Tricocephalus dispar in 

 glycerin, finished in this manner, 

 which are as tight and firm as when 

 first mounted in 1878. 



It hardens immediately. The mo- 

 ment the heated wire is removed the 

 specimen may be cleaned and han- 

 dled without fear. This is, perhaps, 

 its chief advantage over such slow 

 drying fluids as damar and balsam. 

 It never runs in, as white zinc and 

 other cements are so apt to do. 



Cleveland, O. 



Our Histological and Patholo- 

 gical Laboratories. 



BY J. W. CRUMBAUGH, M. D. 



Previous to furnishing and open- 

 ing my microscopical laboratory, I 

 visited those connected, directly or 

 indirectly, with the medical colleges 

 in this and other cities. My greatest 

 surprise was at their primitive meth- 

 ods. The only one I visited that af- 

 forded quick, and mathematically cor- 

 rect, means of work, and that was not 

 open to students, was the one under 

 the direction of Dr. J. J. Woodward, 

 in the Army Medical Museum, 

 Washington, D. C. The very limited 

 time allowed for instruction in this 



