596 REPORT—1905. 
vesicle of one or more infecting byphge, which at once form haustoria in the first 
cells with which they come into contact. 
The substomatal vesicle is always of the same shape and character in the same 
species, but differs very strikingly in the different species, both in shape and 
character, so that it is possible to identify mycelia which resemble one another 
very closely by tracing them back to their infection vesicles. 
The infection phenomena of Puccinia glumarum, P. dispersa, P. Symphytt- 
Bromorum, P, Phlei pratensis, P. simplex and P. coronifera were described in 
detail, 
8. On our Knowledge of South African Succulents. 
By Dr. 8. SCHONLAND. 
9, Finger-and-Toe (Plasmodiophora Brassicz.) 
By GroreE Ports, B.Sc, Ph.D. 
This paper comprises part of the results of experiments conducted at Newcastle- 
on-Tyne and Halle-a.-d.-Saale between October 1899 and July 1902. The work 
was carried out under Professor Potter and Professor Klebs respectively, and to 
both the author wishes to express thanks for valuable guidance and many useful 
suggestions, He had originally intended to give a full account of the whole 
investigation, but considerations of time and space prevented this. He therefore 
had to confine himself to a few points, and in making the selection chose those 
which hinge on the action of calcium compounds in preventing the disease. 
It is shown that the reaction of the soil has an enormous influence on the 
activity of the fungus. Thus acids, eg., sulphuric, phosphoric, and acetic, 
encourage it; while alkaline substances, ¢e.g., quicklime, sodium carbonate, and 
caustic potash, check it, and if sufficiently strong entirely prevent it. It is 
demonstrated that in alkalinity we have a means of preventing the disease, because 
the strength required to stop the active development of Plasmodiophora Brassice 
causes no perceptible injury to the plants. 
The various modes of action which have been attributed to calcium compounds 
in sometimes preventing the disease are discussed in detail. By soil analyses 
and pot experiments it is shown that the soil calcium has not necessarily any 
relation to the disease. Further, any material manurial or poisoning influence is 
repudiated. Where calcium compounds are an influential preventive when 
applied a season or more before the crop is taken, it is shown that the action is 
very probably due to indirectly strengthening the plant by virtue of those well- 
known, but perhaps imper‘ectly understood, inter-related mechanical, chemical, 
and biological effects of the svil, On the other hand, when they are effective when - 
applied about the time of sowing, their effect is due to the reaction produced. It 
is suggested that in practice the best results will probably be obtained by combin- 
ing the medicinal and reaction effects. 
10. A Revised List of the Indigenous Plants of Natal. 
By J. MEDLEY Woop. 
11. Report on Experimental Studies in the Physiology of Heredity. 
See Reports, p. 226. 
