MISSOURI BOTANICAL GARDEN BULLETIN 21 
plants suffer certain disorders, the causes of which it is im- 
portant to know. It is believed that in distilled water the 
food relations play an important réle in the incipiency of the 
disorders, and this has the effect of predisposing the plant to 
the action of bacteria and mold fungi ordinarily present in 
the culture solution. 
Merrill, M. C. Ann. Mo. Bot. Gard. 2: 507-572. In this 
paper a report is made upon an elaborate series of experi- 
ments and determinations regarding the effects of various in- 
jurious agents upon plants. By studying changes in the 
electrical conductivity of water in which the roots of treated 
plants were immersed, it was found that the electrical method 
gives a delicate and reliable measure of the effects of gases or 
other deleterious agents or conditions. Numerous data are 
given regarding the action of the various substances em- 
ployed. . 
Overholts, L. O. Ann. Mo. Bot. Gard. 2:667-730. This 
paper is a critical study of some of the more different groups 
of species of the polypores. A special attempt has been made 
to use ictestonicd ciaraclats in the separation of the 
species ; in short, an attempt to employ more exact characters 
in the determination of closely related forms. 
Overholts, L. O. Washington Univ. Studies 3 (Part I, 
No. 1): 1-84. This is in reality a manual of the polypores 
of the middle-western United States. It should prove serv- 
iceable to all who would have to identify these fungi, many 
of which cause disastrous diseases of trees, likewise important 
timber decays. The manual includes 132 species, with 
analytical and synoptical keys. 
The School for Gardening—The resignation of Mr. 
Charles H. Thompson, Mr. K. Svetlikoff, Mr. C. W. Garrett, 
and Mr. H. M. Biekart has necessitated considerable change 
in the conduct of some of the courses. Temporarily, other 
members of the Garden staff have been carrying this addi- 
tional work, and Mr. G. H. Pring has been added to the per- 
manent corps of instructors. Plans are now under way for 
additions to this staff, and it is expected that early in the year 
1916 the teaching force will be restored to its normal size. 
Mr. Fred G. Grossart completed the course on September 
30 and was awarded a Garden certificate. He is now head 
gardener at Valhalla Cemetery. 
As the result of competitive examination, Mr. James 
Monteith was appointed to the only vacant scholarship on — 
October 1, and besides those holding scholarships there are 
five students paying tuition. : 
