193 



a solution of clove oil eosin stained them densely and then made them 

 plainly visible. The solution I used was made by adding a small quantity 

 of eosin to the pure clove oil. This stains very quickly and must therefore 

 only be allowed to act a few seconds. The aggregate plasmodesmen did 

 not show themselves in this specimen to be perfectly smooth threads of 

 protoplasm but were coarsely granular or appeared considerably thickened 

 at irregular intervals. (Fig. 2.) The solitary plasmodesmen, however, 

 were more miiform. Tliis appearance of the plasmodesmen was only to be 

 seen to good advantage under ver5' high magnitication. The plasmodes- 



Fig. 3. 



men shown in Fig. 2, for example, were magnified 2,250 times. The en- 

 larged ends of the pits aliove referred to are better shown here than in 

 Fig. 1. 



The plasmodesmen in tlie cortex of Aesculus flava were also examined. 

 To do this I removed the outer layers down to the green tissue, and the 

 thin sections obtained there were treated in the same way as those of the 

 endosperm of Phoenix dactylifera, except that instead of using chloriodide 

 of zinc, sulphuric acid was employed for swelling. Clove oil eosin was 

 also used here with good results. Hoffman's blue was also more effective 

 than in the first case mentioned. The plasmodesmen of both kinds were 

 made visible here, although the solitary ones were, as usual, more difficult 

 to distinguish than the aggregate ones. Some experiments in demonstrat- 

 ing the plasmodesmen in moss leaves were also performed. This was done 

 by plasmolysis. The leaves of Funaria hygrometrica, and often whole 



13— A. OF Science. 



