Vol. 6, 1920 
BOTANY I. W. BAILEY 
197 
power of the concentrations, hence are important even in very dilute Solu- 
tions. 
1 Duhem, Mechaniqiic Chimiquc, Livrc VI, Chap. 111. The function Tdif/dT — (p 
is identically equal to Gibbs' heat function U + pv. 
2 Ibid. 
2 Van Laar, Sechs Vortrage u. d. thermodynamische Potential, S. 84. 
^ Technology Quart., Boston, 21, 1908 (372). 
^ Ihid., p. 371. 
6 Adams, L. H., /. Amer. Chem. Soc, 37, 1915 (481). 
7 Maclnnes and Braham, Ibid., 39, 1917 (2110). 
8 Amer. Chem. Jour., 34, 1905; 37, 38, 1907. 
9 Zs. phys. Chem., 31, 1899; and 27, 1898. 
Duhem, lac. cit. 
11 These Proceedings, 3, 1917 (569) ; see also /. Amer. Chem. Soc, 40, 1918 (106-158). 
12 These Proceedings, 3, 1917 (574) and /. Amer. Chem. Soc., 40, 1918 (145). 
THE FORMATION OF THE CELL PLATE IN THE CAMBIUM OF 
THE HIGHER PLANTS 
By Irving W. Baii^ey 
BussEY Institution for Research in Applied Biology 
Communicated by W. M. Wheeler, February 17, 1920 
In a previous note^ the writer called attention to a remarkable type of 
cytokinesis that occurs in the cambium of Coniferae. The process of 
cell plate formation is greatly extended, both as regards space and time 
and is clearly dissociated, except in its initial stages, from the usual phe- 
nomena of karyokinesis. Since this type of cell division promises to be 
of considerable significance in the study of various cytological and physio- 
logical problems^ it is desirable to determine whether it is an isolated phe- 
nomenon, i.e., confined to the Coniferae, or one that is characteristic of 
the cambia of all of the higher plants, angiosperms as well as gymnosperms. 
During the last growing season, I secured specimens of the cambium 
from an extensive series of angiosperms. vSelections were made so as to 
include representatives of all of the larger and more important orders of 
the dicotyledons and of certain arborescent monocotyledons which have 
"secondary" growth in thickness. Specimens were obtained from both 
tropical and temperate environments. 
Although the cambial initials in mature stems of angiosperms are on an 
average considerably smaller than homologous elements of gymnosperms^ 
the salient features of cytokinesis are the same in both subphyla. In 
the former, as in the latter group, each initial contains a single nucleus 
which is centrally located and divides mitotically. The spindle becomes 
extended laterally by the addition of peripheral "fibers"^ and gradually 
assumes the form of a disk, figures A and B. As more fibers are succes- 
sively added the original "connecting fibers" disappear from about the cell 
