MICROCHEMICAL TESTS 673 



Chaze [Bull. d'Histol. Appl., v, 1928, p. 253), studying the 

 formation of alkaloid in Nicotiona seedlings uses a combination 

 of the two following methods : (1) Lightly press young radieles 

 between coverslip and slide and treat with a dilute solution of 

 neutral red. Aleurone grains in process of transformation into 

 semi-fluid vacuoles are stained. (2) Use of Bouchardat's reagent, 

 since aqueous neutral red tends to dissolve the nicotine. 



1353. Nucleus (see also § 623). Shinke and Shigenaga 

 {Cytologia, iv, 1933, p. 189) lind that the chromosomes and 

 nuclear " reticulum " show reactions for thymo-nucleic acid, 

 lipoids and proteins. The reaction (Feulgen) is restricted to the 

 spiral parts of the chromosomes, which are further dissolved by 

 lipoid and nucleoprotein solvents. The karyolymph is a lipoid. 

 The nucleolus contains lipoids, but no thymonucleic acid. The 

 spindle and fibres and phragmoblast are mainly of proteins and 

 lipoids in a mixed or combined form. 



Margolena {Stain Tech., vii, 1982, p. 9) has further examined the 

 application of Feulgen's reaction to plant material. He finds that 

 nucleoli never react except when the sections are specially treated. 

 Lignin, suberin and cutin always react. Unhydrolised yeasts show a 

 number of reddish granules, apparently due to simple oxidation and 

 not to the presence of aldehydes. Hydrolised yeasts show a purplish 

 nucleus. 



The nuclei of some plants do not give the reaction. See also 

 Nemec, Ber. Deut. Bot. Ges., xxvii, 1909, p. 43 ; Kuwada and 

 SuGiMOTo, Protoplasma, iii, 1928, p. 531 ; Westbrook, Ann. Bot., 

 xliv, 1930, p. 1011. 



1354. Volutin. Fix with alcohol, formaldehyde or picric acid 

 solution. Stain with fuchsin or methyl violet. Eosin and gentian 

 violet-iodine (Gram's method) do not stain volutin. It darkens 

 readily with iron-alum haematoxylin, but readily loses the stain 

 on differentiation. It is best to stain with carbol-fuchsin and fix 

 by treatment with aqueous I-KI solution. 



General references, see Chapter XLVI, and Sampson, Bot. 

 Gaz., Ixvi, 1918, p. 32 ; Brunswick, Naturiviss., xi, 1923, p. 881 ; 

 McCuLLOCH, Science, Ixxiv, 1931, p. 634 (apparatus for observa- 

 tion of a small object while flooded with various solutions) ; 

 CzAPECK, Biocheniie der PJianzen, Jena, 1920 ; Molisch, Micro- 

 chemie der PJianzen, Jena, 1913 ; Haas and Hii.l, An Introduction 

 to the Chemistry of Plant Products, London, 1928. 



VADE-Jrecu^f. 22 



