METHODS OF SPECIAL STAINING ETC. 663 



ScHAEDE (Beitr. Biol. Pflanzen, xiv, p. 367) has a modification 

 of Juel's fixative to show spindle structure. 



1329. Cytoplasmic Inclusions. Plant cytoplasm appears to 

 contain three systems of self-perpetuating structures, viz. mito- 

 chondria, plastids and their primordia, and osmiophilic platelets 

 (probably equivalent to the Golgi of animal cells). The majority 

 of the methods used in their study are identical with those used 

 on animal tissues. The behaviour of these methods, however, is 

 more variable with plant material. Bowen stresses the use of 

 fresh material, of freshly mixed solutions, of glass-stoppered 

 bottles and very careful handling of osmicated material. Some 

 at least of the variability of osmium impregnation follows from 

 different conditions of growth of the plant material. Thus Bowen 

 and Buck (Ann. Bot., xliv, 1930, p. 565) find Benda's stain is 

 best on sand-culture material, while the Kull stain is more 

 indifferent. 



The identity of the plant equivalent of the Golgi apparatus is 

 still a matter of controversy. Bowen {Anat. Rec, xxxiv, 1926, 

 p. 143 ; ibid., xxxv, 1927, p. 309 ; Biol. Bull, liii, 1927, p. 179 ; 

 Zeits. Zellf. Mikr. Anat, vi, 1928, p. 689 ; ibid., ix, 1929, p. 1 ; 

 Ann. Bot., xliii, 1929, p. 309 ; Bull. Ton. Bot. Club, Ivi, 1929, 

 p. 33) and Gatenby {Nature, cxxi, 1928, p. 11 ; Proc. Roy. Soc. 

 B civ, 1929, p. 302 ; J. Roy. Micr. Soc, III, 1, 1930, p. 20) favour 

 the osmiophilic platelets, which are best seen by the Kolatchev 

 method. Weier (Proc. Nat. Acad. Sci., xvi, 1930, p. 536 ; La 

 Cellule, 1, 1931, p. 261 ; ibid., li, 1931, p. 51 ; Biol. Bull., Ixii, 1932, 

 p. 126 ; Amer. J. Bot., xix, 1932, p. 659) finds that moss plastids, 

 following osmium and silver impregnations as used by Parat and 

 others, show images similar to those of the Golgi apparatus. 



The " canalieuli " of Bensley {Biol. Bull., xix, 1910, p. 174), 

 alleged to be the primordia of the vacuoles and to resemble the 

 Golgi of animal cells, were obtained chiefly by using neutral 

 formalin-potassium bichromate fixatives. Guilliermond and 

 Mangenot (C. R. Acad. Sci., clxxiv, 1922, p. 692) blackened the 

 same, or similar, structures by silver impregnation methods. See 

 also Guilliermond, Mangenot and Plantefol {Traite de 

 Cytologic Vegetale, 1933, Paris) for numerous references, 



Bowen finds the " vacuome " is most regularly blackened by 

 the Weigl method, but the manner of impregnation is very 

 variable. In fact Patten, Scott and Gatenby {Quart. J. Micr. 

 Sci., Ixxii, 1928, p. 387) consider the vacuome of Bowen may be 

 an artifact, caused by the variability of the water to wash out the 

 corrosive sublimate of Mann's fluid, previous to osmifieation. 



See also Concalves de Cunha, C. R. Soc. Biol., Paris, xcix, 

 1928, p. 1538. 



A further complication is introduced by the presence of pro- 

 plastids (plastid-primordia), which resemble and have been idciiti- 



