1914] CURRENT LITERATURE 337 
shortly after germination, the mycelium coming from the seed coat which is 
infected while still in the ovary. In sterile cultures there is a complete arrest 
of root development. It is concluded that the so-called soil preference of 
Calluna depends upon the maintenance of a biological balance between the 
roots and the root fungi. The disturbance of this balance in soils rich in lime 
is responsible for poor growth in such soils. Probably also the increased bac- 
terial growth in the chalk cultures is detrimental. It is to be hoped that the 
author will make a comparative study of Callwna in its ordinary habitat, where 
the soil is acid and infertile —H. C. Cow es. 
A new Tylodendron.—Wetss" has described a new form of Tylodendron 
under the name T. Cowardi. Particular int in this speci t d 
the secretory canals and primary wood. Wetsssays: “The outer portions of 
the pith have very numerous secretory canals with dark brown contents, very 
like those found in the Medullosae, in cycads, and also in the pith of Poroxylon. 
d 
€se have not been obsetved or described, so far as I know, in any other 
dron, WeEIss agrees with Poronré that Tylodendron is of araucarian affinity. 
recently been described with discoid pith like the Cordaiteae, considerable 
light is thrown on the connection between the cordaitean and the araucarian 
forms, and that the study of this genus promises much along this line in the 
future.—R. B. Tuomson. 
Plant invasion on Hawaiian lava flows.—Thanks to the initiative of 
UB, we are now well informed as to the revegetation of Krakatau. The 
Successive lava flows from Mauna Loa, the age of many of which is exactly 
Known, afford an excellent opportunity for comparable investigations. € 
results of a preliminary study of this sort are given by Forses.” As is well 
known, the lava here is of two well defined sorts, the pahoehoe, which has a 
smooth and satiny exterior and may be ropy, and the aa, which has a cavernous 
and jagged exterior. Ona lava flow of 18 59, no vascular plants were found on 
the aa, though the surface was often white with lichens. To FoRBES’ surprise, 
Ricco ene 
* Weiss, F. E., A Tylodendron-like fossil. Mem. Proc. Manchester Phil. Soc. 
57: Pp. 14. pls. 2. 1913. 
“Forses, C. N., Preliminary observations concerning the plant invasion on 
some of the lava flows of Mauna Loa, Hawaii. Occasional papers of the Bernice 
Pauahi Bishop Museum of Polynesian Ethnology and Natural History §:15-23. 1912. 
