387 
vailed that there were disease-proof varieties of the potato, but this 
was speedily disproved by experiment. In the discussion of the action 
of Bordeaux mixture the rather remarkable statement is made (p. 22) 
that at present there are no clearly defined formulae.” It is difficult 
to understand how anything can be made more definite than the for¬ 
mula given for the Bordeaux mixture in Circular No. 4 of the Section 
ot Vegetable Pathology, U. S. Department of Agriculture, issued in 
July, 1889. While the formula has since been modified, the directions 
there given were sufficiently explicit. 
The second part deals with the experiments conducted by the Royal 
Agricultural Society in Great Britain and Ireland in 1891. These 
experiments were made in various places and under varied conditions, 
and the results were not in any way uniform. In some no benefit was 
reported, while in others it was very marked. The general conclusion 
reached, however, was that when applied at the proper time and in the 
proper way a decided benefit was derived from the use of Bordeaux 
mixture. 
The third part deals with the experiments for checking the disease and 
the culture of the potato in foreign countries. Eleven questions were 
submitted to the representatives ot Great Britain in Austria-Hungary, 
Belgium, Denmark, France, Germany, Netherlands, and the United 
States. These questions related to the varieties usually grown, changes 
ot seed, methods of seeding, frequency of cropping, maimer of cultiva¬ 
tion, manures used, occurrence of disease, precautions taken against 
it, measures to prevent its appearance, remedies adopted, and the 
results of the treatment. We have here a digest of the experiments 
made in the countries mentioned, and it is valuable as a compilation 
of late information. The experiments in Trance, Belgium, and Holland 
are especially referred to, and in some cases given in full. Part 4 gives 
a summary of reports on potato culture in the colonies, mainly those of 
Australia, where, however, the disease either does not exist or does but 
little damage. It occurs to a greater or less extent in the Bermudas 
and on the Cape of Good Hope. —Joseph E. James. 
Sarauw, G. F. L.— Rodsymbiose og Mykorrhizer scerlig hos Skovtroeerne. 
<Bot. Tidsskrift, vol. xvm, Copenhagen, 1893, pp. 134, pi. 2. 
The present paper contains a complete account of the various theories 
and explanations which have been given of the u root symbiosis and 
the Mycorrliizse.” It contains abstracts of a large number of papers 
from the earliest up to the present time, while the original investigations 
of the author are merely alluded to. It should be pointed out that the 
present paper represents only the historical part of a comprehensive 
work entitled “ Bogens Svamprodder,” for which the author was awarded 
the prize of the Royal Danish Academy of Sciences. 
The various forms of parasitism are discussed as “antibiosis” and 
^symbiosis,” terms which were proposed by Vuillemin (1889), and which 
