316 CYTOLOGICAL METHODS. 



then for one day in 0-25 per cent, chromic acid, one in 0-33 per cent, 

 and two to three in 0*5 per cent., wash one day in water, dehydrate 

 and make paraffin sections. Then stain with one of Ehrlich's 

 mixtures, according as the granulations are basophilous, acido- 

 philous, or neutrophilous. The methylen-blue and eosin process of 

 Michaelis is recommended. 

 See also Mallory, 271 and 272 ; Mann, 328. 



673. Mitochondria,* Golgi Apparatus,! Yolk, Fat, and other 

 Cytoplasmic Inclusions. I --The mitochondria and Golgi apparatus 

 never clearly appear in stained sections prepared by such methods 

 as fixation in corrosive acid, Gilson, Bourn, Carnoy or Flemming- 

 with-acetic acid, and staining in Ehrlich's hsematoxylin and eosin, 

 toluidin-blue and eosin, paracarmine and borax carmine. Though 

 the mitochondria and Golgi apparatus are properly fixed by formalin, 

 Miiller, Flemming- without-acetic acid, Champy, Altmann, etc., they 

 will rarely appear visible in stained sections which have been pre- 

 pared in Ehrlich's or Delafield's haematoxylin or carmine stains, or 

 in fact in any of the current laboratory stains used for general 

 zoological purposes. The mitochondria and Golgi apparatus may 

 appear visible in sections fixed in formalin, Miiller, etc., and stained 

 in Altmann's acid, fuchsin-picric acid, iron-hsematoxylin, Benda's 

 alizarin and crystal- violet, etc. The Golgi apparatus rarely becomes 

 visible after any of the above methods, and to study it one must 

 use more specialised methods ; to study the Golgi apparatus and 

 the mitochondria by routine zoological laboratory technique is not 

 possible, simply because these methods will not demonstrate the 

 bodies in question. Nearly all of the older fixing mixtures contain 

 either alcohol, chloroform, or acetic acid, but the last few years of 

 cytological research have shown that the picture given by a fixing 

 mixture containing them is incorrect and inadequate, and one 

 cannot fail to be surprised at the improvement produced when these 

 reagents are omitted. Nearly all the modern research on the cyto- 

 plasm has to be carried out by observers using chrome- or platinum- 

 osmium fixatives, followed by iron-alum hsematoxylin, Benda's 

 crystal violet, or Altmann's acid fuchsin ; or by the important 

 Kopsch and Mann-Kopsch, and Sjovall osmium tetroxide methods ; 

 or by the useful methods of Cajal, Golgi or Da Fano's modification 



* Clioiidilosomes, chondriokonts, plastocliondria, " chromidia," bio- 

 blasts, chondriome, chondriomites, etc., etc. 



t Nebenkern batonettes, idiozome rods, " Golgi-Kopsch apparat," 

 apparato interne reticolare, dictyosomes, Binnennetz, etc. 

 By J. B. G. 



