484 Morphologie etc. — Varietäten etc. — Physiologie. 



formation of a secondary meristem which originates just outside 

 the primary phloem; but as this meristem cuts off cells centripetally 

 it is, in the mature stele, separated frora the primary phloem by 

 all the secondary tissue, usually called prismatic tissue. This pris- 

 matic tissue consists of varying proportions of tracheides, parenchyma 

 and phloem and was interpreted by Stokey as more or less imper- 

 fectl}'' developed xylem. Scott and Hill occasionally found a second 

 more internal meristem, also anomalous in that it produced tissue 

 centripetally onl}'-; they further detected indications of a normal 

 secondary growth, the meristem or cambium here Ijnng between 

 primary xylem and phloem. 



The author compares the two sorts of primary xylem, the inner 

 kind to which the leaf-traces are attached and the outer one of 

 radially arranged tracheides between these leaf-traces to the inner 

 and outer xylem found in certain ferns. So far as can be ascertained 

 in a form in which the central xylem develops so irregularly the 

 protoxylem, as far as recognizable, lies at the peripher}'' of the 

 central mass of xylem, as it is in the ferns to which reference has 

 just been made. On the other band the outer xylem maj^ be 

 compared, in the authors view, to the secondary xylem of the 

 Lepidoäendreae , with which it corresponds in morphological position. 

 It is held that this double comparison is justifiable since in the 

 Ophioglossaceae a sharp line cannot be drawn between outer primary 

 centrifugal xylem and secondar}'' xylem. Isabel Browne (London). 



Campbell, D, H., Plant life and evolution. (New York. Henry 

 Holt & Company. 12 m». IV, 360 pp. 22 f. 1911.) 



A well written untechnical presentation, divided into chapters 

 dealing with factors in evolution; the lower plants; the origin of 

 land plants; seed plants; the Angiosperms; environment and adap- 

 tation; the problems of plant distribution; the human factor in plant 

 evolution; and the origin of species. Trelease. 



Piper, C. V., The protot 5'^ pe ofthe cultivated sorghums. 

 (Journ. Amer. Soc. Agronomy. VII. p. 109—117. Mar. 1915.) 



The forms clustering about Andropogon halepensis are definitely 

 excluded, the wild ancestors of the cultivated sorghums being be- 

 lieved to center about certain forms of A. Sorghnni. Trelease. 



Piper, C. V., M. W. Evans, R. McKee and W. J. Morse. 



Alfalfa seed production; pollination Studie s. (Bull. n^. 

 Ib. U. S. Dep. Agr. Apr. 8. 1915.) 



Gross pollination is found, to increase the proportion of pods 

 set and of seeds per pod; and automatic tripping of the flowers 

 with attendant seif pollination are believed to result in the setting 

 of as many fruits as are due to insect visitors, in the western 

 United States. Trelease. 



Caldwell, J. S., The relation of environmental condi- 

 tions to the phenomenon of permanent wilting in 

 plants. (Physiological Researches. I. p. 1—56, f. 1 — 14. 1913.) 



The author reports experiments bearing upon the questions of 



