44 BOTANICAL GAZETTE. [ February, — 
exogenously each new superadded vessel followed exactly the undulating. — 
course of those upon which it rested.” ce. 
The cortex consisted of three layers, which pass more or less gradu- — 
ally into each other. The outer is composed of parenchymatous cells, — 
_ which are without special order of arrangement; the inner of a zone of 
cells arranged in radial parallel lines; while the middle is a transition — 
with slight distinguishing characters, from the one to the other B 
The origin of the root-bundles which run to the rootlets is as follows: — 
Some of the vessels of the xylem cylinder, or usually, in the initial step, — 
one vessel, instead of pursuing the undulating course, is deflected out — 
ward and forms the basis of one of these bundles. Other vessels are 
____ added to it from time to time, and it thus increases in diameter. Where _ 
__. (these emerge from the bark a lenticular scar is produced, giving rise to — 
of modern Lycopodiacex, particularly of Selaginelia and Isoetes. The — 
latter, like Stigmaria, has a fistular medullary cavity which is produced — 
“by the early absorption or non-development of the delicate parenchyma — 
which ought to be present. The origin of the rootlets is also similar. 
F. H, KNOWLTON. 
thors which appeared a little over a year ago. A number of the figures _ 
_ In the present edition are new, and are especially clear illustrations of the 
of the United States Department of Agriculture, published last year unde? 
th directi of the commissioner of agriculture. In this publication the 
distinctive 
A 
° VIALA, PreRRE, and Ravaz L.—Le Black R i ne 7 
ad ? +L. ot et le Coni diplodiella. (Secon™ — 
ee) 58 pp., 1 colored plate and 15 wood-euts, tmall Sv. Moutpellier and Paris, 
