175 
Only one lithographic table lias been introduced and an effort bas 
been made to simplify the text as much as possible. What is here 
omitted the specialist will find in original papers, which in any event he 
would desire to consult, and the general reader will welcome tbe clear 
style and freedom from technical description. Tbe individuality of tbe 
author is visible everywhere. He has copied no one, not even in tbe 
matter of wood-cuts and the result is an exceedingly interesting and 
useful book. 
The introduction discusses briefly: 
(1) The development of tbe doctrine of plant diseases (commencing 
with Schreger, 1795); (2) Causes of disease; (3) Methods of investiga¬ 
tion. 
The body of the work is divided into four sections: (1) Injuries by 
plants; (2) wounds, i. e., mechanical* injuries; (3) sickeniugs through 
influence of the soil; (4) sickeniugs through atmospheric influences. 
Tbe first section contains 175 pages, the greater part of which is de¬ 
voted to parasitic fungi. Tbe treatment of this subject is somewhat 
broader than the title of the book would indicate, brief mention being 
made of diseases attacking grains, vegetables, and other herbaceous 
plants. 
The author is most at home upon the wood-infesting and tree-destroy¬ 
ing species, to which he has devoted many years of profound and pains¬ 
taking inquiry. The following Hymenomycetes are described as destruc¬ 
tive to living wood : Trametes radiciperda , T. pini ; Polyporus fulvus, 
P. borealis , P. vaporarius , P. mollis , P. sulphureus , P. igniarius , P. 
dryadeus; Hydnum diversidens ; Telepliora Perdix ; Stereum hirsutum, 
aud Agaricus melleus. Mention is also made of Polyporus fomentarius , 
P. betulinus , P. Icevigatus , and P. Schweinitzii , and the author believes 
that numerous other Polypori not yet critically investigated live as par¬ 
asites in tbe wood of trees. Dcedalea quercina and Fistulina hepatica 
are also probably parasitic, at least tbe former. 
Tbe destruction of timber receives considerable attention. There is 
a “ dry rot” due to various fungi, the spores of which often find their 
way into cracks on the surface of logs while lying in the forest. These 
spores germinate the following summer while the logs are at the mill, if 
the heat and moisture are sufficient. The first symptom is a red-strip- 
iug of the timber. The loss from this cause in the Bavarian forest is 
stated to be 33 per cent, of the entire product. The most vexatious 
timber-destroyer appears, however, to be the house fungus Merulius 
lacrymans. This attacks and destroys low lying or damp portions of 
buildings, and is peculiarly a plant associated with men, although it 
sometimes occurs in the forest. The extremely minute spores, about 
four million of which could be packed in the space of a cubic millime¬ 
ter, germinate only in presence of some alkali, and this is thought to be 
the explanation of the fact that the fungus is most likely to appear in 
parts of buildings wet by urine, ashes, etc. When fresh, this fungus 
