908 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Double-sided Slide. — Dr. C. V. Zenger suggests that for viewing 

 both sides of an object the slide should be pierced through in the 

 centre, and the aperture surrounded on the upper and under side by 

 countersunk rings for the cover-glasses to rest on, level with the 

 surfaces of the slide. 



It is to be feared that this plan, though theoretically very perfect, 

 would be too difficult of execution to be practical, though Dr. Zenger 

 writes that " the feat of turning out the slides in their centre without 

 breaking numbers of them is not so difficult as it may seem, if they 

 are well centered and cemented to a cork plate fastened centrally to 

 avoid lateral irregular pressure." He adds, " Such a slide will do 

 extremely good service to the microscopist as well as to the biologist, 

 and amply repays the amount of labour spent on its construction."* 



Dr. W. Krause has also suggested what appears to be a similar 

 arrangement.! 



Uses of CoUodion.t — Mr. E. L. Mark gives an historical account 

 of the development of the use of collodion in histological technique. 



The concentration of the collodion was rendered capable of varia- 

 tion by Merkel, through the use of celloidin dissolved in absolute 

 alcohol and ether in equal parts. Schiefferdecker has shown that by 

 dehydrating sections with 95 per cent, alcohol, and clarifying in oil 

 of origanum or bergamot, they can be mounted in balsam. In com- 

 bination with oil of cloves collodion can be used as a fixture for 

 sections in series, which can be stained after they have been arranged 

 and fixed on the slide.§ Gage || applies the collodion and oil of cloves 

 separately, first coating a number of slides with collodion, which is 

 poured on to one end of the slide and allowed to flow quickly over it 

 and back into the bottle, and then adding a wash of oil of cloves. In 

 order to remove any cloudiness that may arise in the collodion-film a 

 little oil of cloves is added to the balsam. The use of collodion to 

 prevent the crumbling of brittle sections originated with Mr. N, N. 

 Mason,ir who applied it by means of a fine brush, taking up a small 

 drop and placing it in the centre of the object, so as to allow it to 

 flow out on all sides. After being allowed to harden for a minute, 

 the section may be cut and placed on the slide with the film of 

 collodion underneath. 



The following formulse are given for the preparation of celloidin 

 injection-masses. 



A. Asphalt celloidin. 1. Pulverized asphalt placed in a well-closed 

 bottle of ether and allowed to remain 24 hours, with occasional 

 shaking. 



2. The brown-coloured ether is turned ofi", and small pieces of 

 celloidin dissolved in it until the solution flows like a thick oil. 



* See also this Journal, ante, p. 377. 



t Internat. Monatsschr. f. Anat. u. Histol., i. (1884) p. 353. 



X Amer. Natural., xix. (1885) pp. 626-8. 



§ Arch. f. Mikr. Auat., xxii. (1883) p. 689. 



II Med. Student. Nov. 1883, p. 14. 



^ Amer. Natural., 1880, p. 825. 



