396 BOTANICAL GAZETTE [aay 
although this is difficult to prove. The cells and nuclei are found to be distinctly 
larger, as shown by measurements of nuclei of the pollen mother cells and of 
various other tissues. Drawings from transverse sections of the stems show 
clearly the larger size of the cells in the giant form. He concludes that “the 
character of giantness manifests itself in the cells themselves and not merely in 
the plant as a whole.” 
The reviewer has showns* that in Oenothera gigas the cells and nuclei are 
constantly larger than in O. Lamarckiana, but that the ratio of increase varies in 
different cases, the sizes being 1.5:1, 2:1, 3:1, or even more, though apparently 
constant for each tissue esbetied <2. R. GATE 
Secondary growth in monocotyledons.—Evidence against the significance of 
histogenic layers in the stem apex continues to accumulate. ScHouTEs? dealt a 
severe blow to HANSTEIN’s theory when he showed that in Hippuris the plerome 
gives rise not only to the central cylinder but also to part of the cortex. As to 
vascular cryptogams, CAMPBELL‘? found that the vascular bundles of Equisetum 
originate from the cortical region. A monocotyledon has recently been studied by 
CaraNo,‘! who finds that in the young stem and leaf of Yucca aloifolia it is impos- 
sible to distinguish between plerome and periblem. The author concludes that in 
this stem the existence of two distinct regions, central cylinder and primary cortex, 
is absolutely unfounded. It may be objected, however, that in this case there is 
merely negative evidence, which will not settle the question for the monocotyledons. 
In the stem of this plant there is nothing corresponding to the pericycle of the 
dicotyledons, and the meristematic zone which gives rise to the secondary tissues is 
continuous with the apical meristem. Hence this zone is considered to be primary 
at the outset, though the cambial wplgdl later spreads outward to mature cells, 
when the meristem and its products of course become secondary. The perma- 
nently active layer so established he vascular bundles and parenchyma 
internally, and parenchyma externally —M. A. CHRYSLER 
Affinities of an alpine flora.—Following the glacial relic theory postulated by 
Gray and elaborated by Hooker and others, Harvey? has studied the vascular 
flora of Mt. Ktaadn, Maine. Four distinct elements are distinguished: (1) the 
arctic-relic, (2) the pre-glacial alpine, (3) the endemic, and (4) the subalpine- 
lowla Of these the last is regarded as not truly alpine, while the endemic flora 
consists of the single initial endemic Carex Grahamii and the relic endemic 
Gates, R. R., The stature and chromosomes of Oenothera gigas DeVries. 
oe f. Zellforsch. 3:525-552. 1909 
39 ScHouTE, J. C., Die steliar Theorie. Jena. 1903. 
4° CAMPBELL, D. H., Affinities of the genus Equisetum. Amer. Nat. 392273-285- 
1905. : : 
4¢ CaRANno, E., Su le formazioni secondarie nel caule delle Monocotiledon!. 
Annali di Botanica 8:1-42. pls. I-4. 1910. 
42 Harvey, LeRoy H., The floristic composition of the vascular flora of Mount 
Ktaadn, Maine. Mich. Acad. Sci. Report 11:37-47. 1909 
