16 Scientific Proceedings, Royal Dublin Society. 



Starch. — In order to detect the presence of starch, the material which has 

 been immersed in boiling alcohol for a few minutes is then placed aside till 

 decolorized. After decolorization it is washed and placed in a 10 per cent, 

 solution of chloral hydrate for sis hours. Dilute iodine in glycerine was then 

 used for the detection of starch granules. 



Polytrichum commune. 



Hexoses.— Both dextrose and levulose were detected. 



Disaccharides. — The presence of sucrose is indicated by the increase in 

 copper reduction on treatment with invertase under suitable conditions, 

 details as to which are given with the quantitative work. 



CuO reduced after 1-0182 

 „ „ before - 6^75. 



The presence of maltose was demonstrated by the following experiment, 

 100 c.c. of previously inverted extract are treated with 0-2 g. of taka- 

 diastase for 48 his. at 34°, and the copper reduction again noted. 



CuO reduced before T0.32 

 „ after 1-143. 



P. commune is probably one of the most highly specialized of the Musci ; 

 in its massiveness it approaches the vascular plants. The stem often reaches 

 a length of more than twenty centimetres. The leaves, which are confined 

 ro the upper part of the stem, have a thick midrib. On the upper surface 

 are a series of vertical lamellae. These lamellae are responsible for nearly 

 the whole of the assimilation of the leaf, and, in fact, of the entire plant, for, 

 with the exception of the very top, the stem is without chlorophyll. There 

 is much starch in the cells of the lamellae, but the rest of the leaf is com- 

 paratively destitute of it. In the aerial stem is a thick- walled cylinder much 

 of which is composed of starchless elements, which are apparently living. 

 Outside of this lies a thin hydrom mantle (Tansley and Chick (11)). This 

 hydrom mantle is surrounded by a layer of cells from one to two cells thick, 

 which are densely filled with starch. Next to these cells a layer of thin- 

 walled starch-free typical sieve-tubes occurs, rarely more than one cell 

 thick. These leptoids are followed by a layer of very starchy cells, scarcely 

 differentiated from the cortex, which also contains an abundance of starch. 



The hydrom mantle and leptom are in communication with similar 

 elements in the leaf trace. 



Thuidium tamariscin um. 

 This plant is a small fern-like moss, growing in large mats in woods. 



