606 SUMMARY OF CURRENT RESEARCHES RELATING TO 



channel of the rhizoid from being blocked by bubbles. But these are 

 not the only functions of the papillate rhizoids ; for they occur just as 

 freely and as well developed in plants which are so bathed in water that 

 no bubbles could possibly be formed. He thinks it far more likely that 

 the presence of papillate rhizoids in the Marchantiales and their total 

 absence from all other hepatics is just a distinctive morphological 

 character of the group, and that they have not been adapted from the 

 smooth-walled rhizoids to meet a special requirement. They are 

 morphological, not biological. Strangely enough there are two kinds of 

 rhizoid in one genus of the Jungermanniales, namely the thalloid 

 Monoclea They are smooth-walled. But there is no reason to suppose 

 that the narrow sort have in any way developed from the papillate 

 rhizoids of the Marchantiales. Xor is there any close phylogenetic 

 relationship between Monoclea and Marchantiales. 



Luminosity of Moss Leaves.* — A. J. M. Garjeanne discusses the 

 phenomenon of the reflection of light by moss leaves, especially the 

 peculiar golden-green gleam which is seen sometimes in the leaves of 

 Mnium, etc. He describes what he himself observed in the stolons of 

 Milium rostratum growing in a dark, narrow ditch near Venlo, in 

 Holland. A close examination showed him that the back of each leaf 

 was covered by a clinging drop of water, whicli formed a biconvex or 

 plano-convex lens. Further consideration has led him to the con- 

 clusion that the peculiar luminosity is due to the double reflection 

 undergone by the incident rays of light within this aqueous lens on the 

 back of the leaf. It is mostly the younger leaves of the stolons which 

 behave in this way. 



Types of Tropical Mosses, f — K. Giesenhagen gives an account of 

 the principal types of moss-life in tropical forests of the rain-zone, and 

 the way they adapt themselves to their environment. He describes the 

 external factors that affect the plants, the most important being the 

 saturated condition of the atmosphere. He thus discusses the types 

 of moss-associations. 1. Orthotropic, including humble tufts, tall tufts, 

 and moss cushions. 2. Plagiotropic, including mats and lax tangles. 

 He also divides the solitary mosses biologically into (1) terrestrial, 

 including simple erect stems with distant leaves, and simple erect stems 

 with a crown of leaves at the top ; (2) epiphytic, including frond-like 

 and pendulous. He gives examples of each type, and discusses them in 

 some detail. Finally, he gives a list of 105 mosses and 74 hepatics 

 collected by him in Sumatra, Java, and Ceylon. 



Inter-relationships of Bryophyta.J — F. Cavers continues his 

 account of the inter-relationships of the Bryophyta. First he treats of 

 the two views that may be taken, either that the Marchantiales form 

 an ascending group, starting from Riccia and culminating in Marchantia : 

 or that they show wholesale reduction, starting from a type like Marchantia 

 and having in Riccia the most reduced member of a descending series. 



* Beih. Bot. Centralbl., xxvi. lte Abt., (1910) pp. 1-6 (pis. and figs.). 



t Ami. Bot. Jarcl. Buitenzorg, 3e Supp. (1910) pp. 711-90 (2 pis. and figs.). 



X New Phvtologist, ix. (1910) pp. 193-234 (figs.). 



