158 



even treble height remained obstinately closed. Yet thèse 

 latter contain as well an adventitious bud and not seldom 

 even more than one. 



The microscopical investigation was for the greaterpart 

 carried out on microtome préparations. For fixing the mate- 

 rial I used the mixture: zincchloride-glacial acetic acid- 

 alcohol, (2 grams of zincchloride and 2 ccm. of glacial 

 acetic to 100 ccm. of alcohol of 45 — 50pCt), recommended 

 by J u el '). The particular hardness of the leaf tissue made 

 it necessary to treat the material, before being embedded 

 in paraffin, during 3 to 4 x 24 hours with a 40 pCt. 

 aqueous solution of hydrofluoric acid. After this treatment 

 it was then washed for 8 to 10 hours in streaming water, 

 dehydrated by the usual method and after treatment with 

 chloroform embedded in paraf&n (melting point 62" C). 



For staining the sections I used ad first Haematoxylin- 

 Delafield and saffranin, according to the prescriptions given 

 in Chamberlain's „Methods in Plant Histology" '') ; but 

 this method proved unsatisfactory for differentiating the 

 very thin-walled meristem cells. Therefore I afterwards 

 always stained with methyl green and acid fuchsin ^), by 

 which very good results were obtained. 



A conséquence of the treatment with hydrofluoric acid 

 was that the microtome préparations were not suitable 

 for ail observations. In thèse cases I used hand-cut 

 préparations, if necessary stained with Haematoxylin- 

 Delafield. 



The anatomy of the normal leaf, on which something 



1) H. 0. J u e 1, Ueber den Pollenschlaucli von Cupressus. (Flora. 

 Bd. 93. 1904. pag-, 56—62). 



2) C. J. Chamberlain, Methods in Plant Histology 2nd éd. 

 Chicago. 1905. pag. 30, 38 and 54. 



3) C h a m b e r 1 a i n. 1. c. pag. 40, 44 and 68. 



