and Laboratory Methods. 2425 



of the red bone marrow by the method of Smith (I, 2) and stain with the appro- 

 priate stains mentioned in the next preceding section. 



8. For Preserving and Staining the Finer Structure of the Nuclei. — Uskoio (1890) 

 lays great stress upon instantaneous drying of blood films for the preservation 

 of the finer structure of the nucleus, the most minute chromatin network being 

 preserved. Blood films made very thin and waved in the air to hasten drying 

 would probably accomplish the desired result. Some of the methods of fixing 

 fresh undried blood (II, A) might possibly give even better results. 



Haematoxylin is undoubtedly the best nuclear stain for bringing out the finer 

 structure. Either Ehrlich's haematoxylin and eosin (III, C, 2), Delafield's 

 haematoxylin, Mayer's hcemalum (III, A, 3, b) or Mannaberg's alum haematoxy- 

 lin (III, A, 3, a) is recommended. 



9. For Fixing and Staining the Blood Plates. — Hlava (1883) used methyl eosin 

 and gentian violet (III, C, 5) for demonstrating blood plates in preparation 

 heated over the flame or fixed in concentrated sublimate solution or alcohol. 



Schi7nmelhiisch (1S8(J) also made use of the dry method for studying blood 

 plates. The dry intact plates are said to stain with concentrated watery or alco- 

 holic solutions of methyl violet, fuchsin, anilin green, etc. 



T?^?/'/ (1896) stained the blood plates with iron haematoxylin of E. Haiden- 

 hain (for the demonstration of centrosomes). 



Bodie and Russell {y^^l^ used a sodium chloride solution with a dahlia stain 

 to prevent clumping of the blood plates. 



Their formula is, — 



Dahlia-glycerin - . . _ "^ 



2 per cent, sodium chloride - - S P • 



Ehrlich (1900) recommends the iodih-eosin test for glycogen in the blood 

 (see Ehrlich and Lazarus, Histology of the Blood) which differentiates the blood 

 plates. 



Rosin fixed the dry preparations for 20 minutes in osmic acid vapor, and 

 then stained with a concentrated watery solution of methylen blue. 



The polychrome neutral stains of Jenner (III, D, 5, 1), Leishman (III, D,.5, m), 

 Goldhorn (III, D, 5, o) and Wright (III, D, 5, q) and the successive staining 

 with eosin and methylen blue after the method of Engel (III, D, 5, g), Japha 

 (111, D, 5, h) and Goldhorn (111, D, 5, i) preserve and stain the blood plates. 



Deetjen (1901) demonstrated the nucleated condition of blood plates. He 

 believes that the failure of previous investigators to discover this is due to over 

 fixation. Preparations fixed sufficiently for the preservation of the hemoglobin 

 are over fixed for this purpose. He fixes in alcohol followed by formalin 

 (11, B, 2, c) and stains with Ehrlich's (111, C, 2, a) or Delafield's haematoxylin 

 (HI, A, 3). The nuclei of the plates are stained clear blue; double stain with 

 eosin shows a protoplasmic zone. The nuclei are still more apparent, since the 

 protoplasm is more expanded, in preparations spread upon agar to prevent the 

 thin blood film from drying before fixatives can be applied. This is accom- 

 plished as follows: In a 1 per cent, solution of agar filtered, is dissolved O.G 

 per cent, of sodium chloride, 0.6 per cent, of sodium metaphosphate and about 



