660 
multitude of experiments made by the writer 
and his assistants” and that “it has often 
happened that the ink on some chapters would 
scarcely be dry before the results obtained 
from new experiments would require some 
part of it to be rewritten.” We are further 
told that in this way some chapters were 
“yewritten a dozen times, in whole or great 
part.” These quotations will serve also to give 
some idea of the method of science, and of 
the infinite pains which must be taken before 
final results are attained. 
As indicated by the title of this volume, it 
deals with the history of the subject, that is, 
with the successive investigations of workers 
in this field of science. Some of the pro- 
nouncements of the earlier pathologists now 
make “mighty interesting reading,” as shown 
by the quotations which are liberally given on 
pages 9 to 20. Then follow nearly two hun- 
dred pages of “general considerations” in 
which are discussed such questions as “the 
supposed normal occurrence of bacteria in 
plants” (which is decided in the negative) ; 
“bacteria on the surface of plants”; “ para- 
sitism ”; “inception and progress of the dis- 
ease”; “reaction of the plant”; “symbiosis,” 
ete. The remainder of the book (about 150 
pages) is devoted to “Vascular Diseases,” 
that is, the diseases which have to do with the 
vessels of plants. 
Three vascular diseases are fully discussed, 
namely, the “ Wilt of Cucurbits,” the “ Black 
Rot of Cruciferous Plants” and the “ Yellow 
Disease of Hyacinths.” These are severally 
due to the invasion of the tissues by Bacillus 
tracheiphilus Smith, Bacterium campestre 
(Pammel) Smith, and Bacterium hyacinthi 
Wakker. As one reads the pages of descrip- 
tions he is impressed with the thoroughness 
with which the work upon which they are 
based was done. At every step one sees the 
results of the most painstaking investigation, 
much of which extended through many years. 
And with it there grows the feeling that here 
at last we have contributions to plant pathol- 
ogy that rest upon solid foundations and from 
which guesses and inferences have been 
wholly omitted. 
SCIENCE 
[N.S. Vou. XXXV. No. 904 
In the introduction (page 4) we are given a 
convenient grouping of the diseases of plants 
due to bacteria, viz.: (1) The vascular dis- 
eases, (2) the parenchyma diseases without 
hyperplasia and (8) cankers, tubercles and 
tumors in which there is a more or less dis- 
tinct hyperplasia. It will appear from this 
that the author has treated but one type or 
group of diseases, and from this we may infer 
that this volume is to be followed by one or 
more others, although no hint is given us by 
the author as to his intentions. It is to be 
hoped that Volume III. will appear in due 
time and that if this be not enough still others 
may follow. We can not help wishing that 
the plant diseases due to the fungi might find 
an investigator who would do for them what 
Dr. Smith is doing for those due to bacteria. 
CuHarurs E. Brssry 
THE UNIVERSITY OF NEBRASKA 
Corrosion of Iron and Steel. By J. Newton 
Friend, Ph.D. Longmans Green & Co. 
1911. Pp. 300; 62 figures. 
Of the many references to the literature of 
the subject cited by the author, none is more 
interesting than the following from Pliny 
written some 2,000 years ago. In his “ Nat- 
ural History” Pliny writes “there is a kind 
of hallowing iron within the city called 
Zeugma, seated upon the Euphrates, where- 
with King Alexander the Great some time 
bound and strengthened the bridge over the 
river there; the links whereof, as many as 
have been repaired and made new since, do 
gather rust, whereas the rest of the first ma- 
king be all free therefrom.” Evidently at this 
very early date the observation had been made, 
not only that iron rusts, but that different 
pieces may rust at different rates. The gen- 
eral subject has received so much attention 
from men in widely differing fields, and their 
publications have appeared in so great a num- 
ber of places, that there existed a need for a 
work which would thoroughly digest this 
literature and gather together that portion 
which seemed sufticiently reliable to be of serv- 
ice to the investigators of the present. This 
task, which has not been an easy one, Dr. 
