131 
_tory and affinities of the group, their classification, and contains a 
tabular key for the identification of genera and species. This first 
installment of Part II. deals with eight species of Mitel/a, several of 
which are new. It is begun by a revised synoptical key to the 
thirteen species which Dr. Allen now has from America, five of 
which he has made known. Fourteen plates are issued with the 
fascicle, eight of them lithographs and six photogravures, made 
directly from herbarium specimens, and illustrating very well the 
habit and mode of branching of the plants. . si ae Be» 
Composite—Observations on the—IT, Edward L. Greene (Erythea, 
1. 41-45). 
Prof. Greene refers his recently proposed genus Diolettia to 
Trichocoronis and discusses Eupatorium and its allied genera. 
Conifere—Notes on West American,1. J. G. Lemmon (Erythea, i- 
48-5 2). 
Mr. Lemmon describes his new varieties of Psewdotsuga taxi- 
Jolia; one, var. suberosa from Arizona and New Mexico; the other, 
var. elongata from the base of Mt. Hood, Oregon. He also takes 
issue with Dr. M. T. Masters as to the common name of this tree, 
Maintaining that it should be Douglas Spruce, not Douglas Fir. 
Corky Excrescenses on the Stems of Zanthoxylum—The Nature and 
Development of. C. A. Barber (Annals of Botany, vi. No. 22) 
The author first describes the development of the thorn at 
whose base the corky cushion always originates. The thorn is 
said to complete its growth during the first summer, growing from 
a zone of meristematic cells near its base. In the autumn begins . 
the development of the cork-cells, probably from the same meri- 
stem which produced the cells of the thorn, though the author 
does not expressly state this. Yearly deposits of this cork-tissue 
are made which he compares to the annual rings of Pinus 
stems. As this cushion increases, the tissues near the base of 
the thorn gradually weaken; finally a rupture occurs by which 
it is detached, sometimes leaving a slight scar. In regard to 
the biological significance of this corky growth no explanation 
is attempted; as to determine this he says a careful study of the 
plants in their native surroundings is necessary. In some general 
notes on cork formation in thorns of different plants, several ex- 
planations of other authors are given. In conclusion, the author | oS 
