BOTANY 553 



There is no appreciable difference in the early stages of the 

 two types of gametophyte, which develop from the pear-shaped 

 zoospores as a germination-tube with a terminal swelling into 

 which one of the two daughter nuclei of the original nucleus 

 passes. 



In Laminaria the male gametophyte is much smaller than 

 the female, and consists of smaller more numerous cells, any 

 one of which may function as an antheridium producing a 

 single antherozoid. The female gametophyte is often only 

 one-celled, and this functions as an oogonium, producing a 

 single e.gg which is fertilised after emergence. 



The gametophytes of Chorda, whilst similar in essentials 

 to those of Laminaria, are much larger and irregularly 

 branched. 



Morphology and Anatomy. — ^A study of the floral anatomy 

 of the Urticales carried out by Bechtel {Amer. Journ. Bot., 

 October) has led him to conclude that the flowers are typically 

 zygomorphic and that the bicarpellate condition has been 

 derived by reduction. The latter is indicated by the presence 

 of what are regarded as the vascular strands of suppressed 

 carpels. In Ulmus one outer whorl of stamens and one inner 

 perianth whorl are held to have been suppressed, and the basal 

 orthotropous ovule is regarded as derived from a primitively 

 anatropous condition. 



The study of Phaseolus seedlings with three cotyledons and 

 two primordial leaves by Harris and his colleagues {Ann. Journ. 

 Bot., October) shows that anatomically, as well as morpholo- 

 gically, these are intermediate between typically dimerous and 

 typically trimerous seedlings. In a later paper (November) it 

 is shown that there is a negative correlation in the hypocotyl 

 of trimerous seedlings between the number of double bundles 

 and the number of accessory bundles characterised by the 

 absence of protoxylem elements. 



From a study of various species, especially Vitis vulpina 

 (New York Agr. Exp. Sta., 191 S), Benedict concluded that 

 senescence in the individual was accompanied by a decrease in 

 size of the vein islets of the adult leaf. Ensign, who has 

 recently investigated the point on six species, including Vitis 

 vulpina {Amer. Journ. Bot., November), finds no evidence of any 

 such correlation. 



In an interesting paper dealing with the Norfolk species of 

 Utricularia {Trans. Norfolk and Norwich Nat. Hist. Soc, 

 vol. ix, 1 921), Clarke and Gurney state that stomata are ap- 

 parently absent from the submerged leaves of U. vulgaris, but 

 occur regularly on those of U. intermedia, and less frequently 

 on the leaves of Utricularia minor f. platyloba. 



The occurrence of seasonal growth-rings in a monocotyledon 



