350 SUMMARY OF CURRENT RESEARCHES RELATING TO 



mass separates off from the glass plate, thus setting free the two 

 celloidin layers with their inclosed sections, the whole forming a 

 flexible but tough plate, which may be handled like a rag. Staining 

 and washing are carried out in the usual manner, and after differ- 

 entiating in the ferrocyanide of potassium, the series are again 

 immersed in water, frequently changed, for at least one hour. 



The celloidin section plate may be now cut up under water into 

 as many pieces as there are sections. These are then dehydrated in 

 90-96 per cent, alcohol and cleared up in creosote or xylol. Such 

 sections must remain in alcohol much longer than ordinary ones, as 

 the celloidin layers are slow in dehydrating. From the preparation of 

 the plates to the immersion in hsematoxylin it takes about one hour 

 to produce 100 sections. 



The author has recently discovered a medium to replace creosote 

 (which is dear and malodorous), in a mixture of benzine and alcohol. 

 He hopes to be able to publish his results very shortly. 



Preparation of Picro-carmine.* — Prof. G. Bizzozero prepares an 

 excellent picro-carmine in the following manner : — 



A solution of • 5 grms. carmine, 3 cc. ammonia, and 50 cc. dis- 

 tilled water, is made in a mortar. In another mortar is made a 

 solution of 0'5 grm. picric acid in 50 cc. water. The picric acid 

 solution is then poured slowly into the carmine solution. The com- 

 bined solutions are then heated in a water-bath until every trace of 

 ammonia has disappeared. By this time the bulk of the fluid is 

 reduced to half its previous quantity. It is then allowed to cool, 

 and one-fifth of its volume of absolute alcohol is added. The fluid 

 must be kept in a carefully corked bottle. It is not necessary to 

 filter before using. 



Picro-chromic Acid.f — This is recommended by Prof. H. Fol as 

 an excellent hardening agent for very small pieces of tissue. It acts 

 slowly, having little power of penetration. It is made as follows : — 

 Picric acid (saturated aqueous solution), 10 parts ; chromic acid 

 (1 per cent.), 25 parts; water, 65 parts. A little osmic acid ('005), 

 added shortly before using, is said to strengthen its action much. 



The staining capacity of objects is not impaired by this mixture. 

 The objects should be washed in water. The extraction of the acid 

 is more complete and rapid if nearly boiling-hot water is used. 



Minot's Picric-acid Carmine.j: — Dr. C. S. Minot's carmine is 

 made as follows : — 



Boil 1 grm. best powdered carmine with 200 c.cm. of water, plus 

 an excess of picric acid for half an hour ; allow it to stand and cool ; 

 decant the clear fluid, add fresh water, and, if necessary, picric acid ; 

 boil, cool, and decant ; repeat this operation until all the carmine is 

 dissolved. Place the decanted fluid in an evaporating dish, add 



* Zeitschr. f. Wiss. Mikr., ii. (1885) p. 539, from Bordoni-Uflfredduzzi, ' I Micro- 

 parassiti,' Torino, 18S5, p. 97. 



t Fol's Lehrb. d. Vergl. Mikr. Anat., 1885, p. 100. 



J Whitman's ' Methods in Microscopical Anatomy and Embryology,' 1885, 

 p. 42. 



