30 TansZey and Chick. — Notes on the 
‘ Leitparenchym.’ The cortex is narrow and there are only 
about six or seven traces present outside the hydroid cylinder. 
These, except for the fact above noted, are of quite the same 
type as in the other species. 
III. The Nature and Origin of the Conducting 
Tissues in Mosses. 
Unger 1 was the first to compare the ‘ central strand ’ found 
in the great majority of moss-stems with the vascular strand 
of a higher plant, while he and Lorentz 2 discovered and 
described the leaf-bundle and the leaf-trace which sometimes 
continues the leaf-bundle downwards into the stem. Lorentz 
also discovered the remarkable fact that in some cases the 
leaf-traces end blindly in the cortex of the stem (‘ falsche 
Blattspuren ’), while in others they join on to the central 
cylinder, as in the Vascular Plants ( 4 echte Blattspuren’). 
Haberlandt, in his ‘ Beitrage,’ advanced the whole subject 
enormously by giving definiteness to the previously vague 
attribution of the function of ‘ conduction ’ to these tissues, 
showing by experiment 3 that the central strand of most 
moss-stems is a water-conducting channel, a rudimentary 
‘ Hadrom,’ and that in Polytrichaceae there are in addition 
tissues which function as conductors of plastic food-material, 
both carbohydrate and nitrogenous. In the second section 
of the present ‘ Notes ’ we have shown that in both rhizome 
and aerial stem there is a layer of starchy parenchyma between 
hydrom and leptom, just as in all vascular plants (Russow’s 
‘Xylem-scheide’ in Ferns), and also indications of a rudimen- 
tary pericycle outside the leptom of the aerial stem. In fact 
there are parallels among the Polytrichaceae for all the main 
categories of the stelar tissue of the true vascular plants with 
the exception of primary phloem-fibres, which are always rare. 
1 Beitrage zur Physiologie der Pflanzen : vii. Ueber den anatomischen Bau des 
Moosstammes. Sitzungsb. d. Wien. Akad., 1861. 
2 Grand linien. 
3 Ber. d. Deutsch. bot. Ges., 1883. 
