No. 2, November, 1920] MORPHOLOGY, ETC., VASC. PLANTS 105 



750. Yami'olsky, Cecil. Further observations on sex in Mercurialis annua. Amer. Nat. 

 54: 280-284. 1 jig. May-June, 1920.— -Author grew four plants of .1/. '< annua from 

 seeds collected from a monoecious individual. In general habil of growth these four plants 

 were like typical female plants. During the earlier part of the flowering season only female 

 flowers were produced in each of the plants; later on male flowers and hermaphroditic flowers 

 appeared along with the female flowers, the latter usually being more numerous than either 

 of the others. Author suggests that sex is not a fixed condition in these forms of Mercurialis 

 annua and that a plant may change its sex during the progress of its life cycle. — Chester A. 

 Darling. 



751. Zelexy, Charles. Germinal changes in the bar-eyed race of Drosophila during the 

 course of selection for facet number. Proc. Indiana Acad. Sci. 1917: 73-77. 1918. — Writer se- 

 lected for low facet- and high facet -number in the bar-eyed race of Drosophila. Selection 

 was effective in both lines. Analysis of the results brings out the following facts: (1) The 

 presence of germinal differences, — accessory unit factors, — at the beginning of selection. 

 (2) The appearance of accessory genes during the progress of selection. (3) A change in the 

 bar gene itself causing a return to full eye both somatically and germinally. — Another point 

 of interest is the return of bar eye to full eye by a second route, namely, the appearance of a 

 modifying factor in one of the autosomes. — F. Payne. 



MORPHOLOGY, ANATOMY AND HISTOLOGY OF VASCULAR 



PLANTS 



E. W. Sinnott, Editor 



752. Anonymous. Anatomical modification of roots by mechanical action. [Rev. of: 

 Bloch, E. Concerning the modifications produced in the structure of roots and stalks by ex- 

 ternal compression. (French.) Compt. Rend. Acad. Sci. Paris 158: 1701. 1914.] Sci. 

 Amer. Monthly 1 : 262. 1920. 



753. Bailey, Irving W. The formation of the cell plate in the cambium of the higher 

 plants. Proc. Nation. Acad. Sci. [U. S. A.] 6: 197-200. 8 fig. Apr., 1920.— "A remarkable 

 type of cytokinesis," previously reported by author for the cambium of the Coniferae, is now 

 shown to occur in cambial initials of various representative angiosperms. Author states 

 same phenomenon is found in other somatic cells "whose planes of division have one long and 

 one short dimension." Comparative study indicates ordinary process of cell plate formation 

 is simply extended in space and time where cell dimensions require it, to the limiting case 

 where two widely separated "kinoplasmasomes" are formed at the free ends of the advancing 

 cell plate. — Howard B. Frost. 



754. Barratt, Kate. A contribution to our knowledge of the anatomy of the vascular sys- 

 tem of the genus Equisetum. Ann. Botany 34: 201-236. PI. 8-9, fig. 1-7. 1920.— A detailed 

 description of the vascular system of Equisetum, particularly of the developmental stages in 

 the sporeling, is given. The thoroughness of the work was made possible by a technique which 

 rendered whole sporelings and pieces of the adult transparent so that the vascular system could 

 be viewed as a whole. At the base of the young sporeling is a protostele which opens out into 

 a siphonostele at the attachment of the vascular supply of the secondary axis and then closes 

 again for a short distance. The basal regions of the several axes formed before a rhizome 

 appears show compact siphonosteles. These axes arise endogenously whereas the whorled 

 aerial axes develop from superficial cells. Contrary to views held by some workers the meta- 

 xylem of the vegetative axis all develops centrifugally; nor do any metaxylem strands cross 

 the outer surface of the nodal wood, for they are linked together at this point by short nodal 

 tracheids. There is no trace of secondary thickening at the nodes, the apparent increase in 

 the number of elements attributed to secondary growth being really due to the displacement 

 of developing tracheids. The conditions found in the cone lead the author to conclude that 



