Notes . 
ll 7 
they did not venture to name, consists of ripe sclerotia of the same species, and 
Thwaites 1013, Tuber zeylanicum , is another sclerotium. The latter is much larger, 
about one centimetre in diameter ; it is quite common on rubbish heaps, and when 
planted in damp sand, it produces a white mycelium which runs along the top of 
the sand and forms sclerotia of the same size as those of Sclerocystis coremioides. 
It may, however, be a different species. 
Up to the present it has not been possible to develop a fructification from 
these sclerotia : in pure sand, the larger develop a mycelium which produces the 
sclerotium stage again, while the smaller have not yet produced anything. It seems, 
however, worthy of record that the description of Sclerocystis coremioides was based 
on a complete misapprehension of the nature of the specimen sent from Ceylon by 
Thwaites, and that the genus Sclerocystis , as described, has no real existence. 
Cesati established a new genus Xenomyces , on a similar production collected 
by Beccari in Sarawak. He states that it is ‘ Genus affine Sclerocystidi B. & Br., 
nec minus enigmaticum.’ The description suggests that it is another sclerotium, 
if not the same species as Berkeley and Broome’s. 
Peradeniya. T. PETCH. 
THE CYTOLOGY OF RHOEO DISCOLOR.— At the suggestion of my 
teacher, Prof. Marcus Hartog, I made a preliminary study of the cytology of 
Rhoeo discolor , Hance ( Tradescantia discolor , Plortt.), in 1905. Its inflorescence 
is a compact double scorpioid cyme, which facilitates the assemblage of sets of 
consecutive stages. Many fixatives were tried; but Tellyesniczky’s mixture 
(potassium bichromate, 3 grms. ; glacial acetic acid, 5 cc. ; water to 100 cc.) 
proved most satisfactory. 
Much preliminary work was done ; but other duties make it probable that my 
complete results may long await publication. The two essential points of interest 
are (a) the small number of chromosomes (4-8); (£) the small size of the cells, 
which enables a considerable number in various stages to be seen in a single field 
under a magnification of 500 diameters. This may make the plant a very useful 
object to the cytologist — all the more as it is usually in flower all the year round, in 
hothouses. 
W. J. GALLAGHER 
(From the Biological Institute of Queen’s College, Cork). 
Kuala Lumpijr, Federated Malay States, 
May, 1907. 
A PHOTOELECTRIC THEORY OF PHOTOSYNTHESIS.— The following 
is a preliminary abstract of an investigation into the nature and mode of formation 
of the primary products in photosynthesis, which has been carried out in my 
laboratory at intervals during the past three years. Although the general hypothesis 
underlying this research was formulated some twelve years ago, various circumstances 
interfered with all but preliminary experiments until 1905, when the investigation 
was resumed. 
