I4 2 BOTANICAL MICROTECHNIQUE. 



[Mangin states (VIII) that the most important and most 

 characteristic reaction of cellulose is its conversion into 

 hydrocellulose or amyloid. This conversion is not certainly 

 accomplished by acids, but the best results are obtained by 

 treating the cellulose with a saturated alcoholic solution of 

 sodium or potassium hydroxide and then transferring it to 

 absolute alcohol. Cuprammonia also produces the same 

 result. The above-described reagents for cellulose act 

 promptly with hydrocellulose.] 



247. Their behavior with staining media can also be used 

 for the recognition of pure cellulose membranes. These 

 also serve in delicate sections, microtome sections or the 

 like, to bring out better the network of cell-walls. 



Hcematoxylin is especially adapted to this purpose, Giltay 

 (I) having first observed the fact that it stains deeply only 

 the unlignified and unsuberized membranes. It may be 

 used in very various solutions (e.g. in the so-called Bohmer's 

 (cf. 315) or in Delafield's (cf. 314) solution). These stain 

 pure cellulose walls deep violet, while lignified and suberized 

 membranes remain at first uncolored, or are stained yellow 

 or brown. In most sections an exposure of a few minutes 

 is sufficient for a deep staining of the membranes. 



248. The writer has used haematoxylin with the best 

 results for the recognition of the closing membrane of bor- 

 dered pits (Zimmermann IV). With the wood of Conifers 

 it is sufficient to leave the sections for fifteen minutes in 

 Bohmer's hsematoxylin solution (cf. 315) to obtain a deep 

 staining of the " tori " of the bordered pits, which, naturally, 

 come out most sharply after clearing in Canada balsam (cL 

 14-22). 



249. Aniline blue and methyl blue may also be used for 

 staining cellulose walls. These produce an intense stain in 

 an hour with microtome sections, which is not affected by 

 alcohol, clove-oil, or xylol, so that the preparations may be 

 mounted in Canada balsam. A solution of Berlin blue acts 

 in the same way. This is prepared by allowing I gram of 

 soluble Berlin blue and .25 gram of oxalic acid to stand sev- 

 eral hours with a little distilled water, then adding 100 ccnu 



