GOLGI BODIES ETC. 313 



mitochondria. Golgi apparatus, yolk and fat, are nearly always 

 mixtures of different quantities of several definite substances, and 

 consequently will reduce the osmic solution in varying degrees 

 of intensity. Kopsch methods are somewhat capricious, but 

 one gets results unequalled by other methods ; for chrome- 

 osmium, or chrome-formol, followed by iron ha^matoxylin, or 

 Altmann generally will not demonstrate the Golgi apparatus 

 (except in male germ-cells), while the Kopsch methods preserve 

 and demonstrate Golgi apparatus, mitochondria, yolk, fat and 

 chromatin structures, and occasionally neurofibrils of embryos 



For this method dissect out organs, and cut tissue into small 

 pieces ; dip these quickly into aq. dest. to remove blood or cell 

 detritus from surface, and then transfer to a small glass-stoppered 

 or glass-covered capsule of 2 per cent. OsO^. Leave in a darkened 

 cupboard for two weeks (fourteen days) at room temperature. 

 Wash in running water for several hours, dehydrate, imbed in 

 hard wax ; section about 3 /a. Mount unstained, or stain 

 chromatin in safranin or methyl-blue eosin. Unsaturated fats 

 black, others yellowish, Golgi apparatus and sometimes mito- 

 chondria, black. 



This method succeeds for mollusc and many invertebrate 

 tissues, but it may be taken as superseded by the Mann-Kopsch 

 and Kolatchew methods (§§ 710 et seq.). Some workers may object 

 to the preliminary fixation in corrosive osmic of the Mann-Kopsch 

 method, but the Kolatchew method has a preliminary fixation in 

 Champy's fluid, and may be preferred. 



709. J. Bubenaite's Method for the Golgi Apparatus. Fix for one or 



two days in 10 per cent, formalin. Transfer to 2-5 per cent, aqueous 

 bichromate of potash or Miiller's fluid for two days at 34° C. Rinse 

 in 2 per cent. AgNO.,, and transfer to the same solution for one to two 

 days at 34° C, Imbed and mount as usual. In our hands this pro- 

 duced dreadful results. 



710. The Weigl or Mann-Kopsch Method (Weigl, Bull. Acad. 

 Scien. Cracovie, 1912 ; Hirschler, Arch. mikr. Anat. 89). For 

 a study of cell structure, and in general cytology, the Weigl or 

 Mann-Kopsch method gives invaluable results. It is an alternative 

 to the formalin-silver nitrate techniques of Cajal or Da Fano, 

 but in addition preserves fatty substances. 



The Weigl or Mann-Kopsch technique in itself is easy to work, 

 but the subsequent steps in staining are often extremely difficult. 

 The ordinary Kopsch technique may cause extreme shrinkage, 

 and is not generally so specific. First fix in Mann's osmo-sublimate 

 fluid (§ 76) for from one quarter-hour to two or three hours or 

 more. Pieces to be fixed must be small (not exceeding a centi- 

 metre in diameter) and should only be left in the osmo-sublimate 

 long enough to complete the penetration of the fluid. For an 

 insect ovary, or small invertebrate, one half-hour is sufficient ; 



