54 Morphologie etc. — Varietäten etc, 



rangial mechanisms ofthe seed plant s. 'Bot. Gazette. LXII. 

 p. 281-292. PI. 7—9. 1916.) 



In Ginkgo the opening mechanism is clearl}'^ an adjunct of the 

 transfusion tissue of the fibrovascular System and is directly conti- 

 nuous with this. 



A similar condition of relationship between the tracheary tis- 

 sues and the dehiscing mechanism of the microsporangium is like- 

 wise found in the Ahietineae among the conifers. In the remaining 

 conifers (and including the araucarians) the sporangial mechanisms 

 are much reduced and no longer have a relation to the vascular 

 bundles of the sporophyll. 



In the angiosperms the fiber layer of the anther wall is usually 

 well developed and is of internal origin, but has no connection with 

 the fibrovascular system, even in the forms regarded as low. 



P'rom the Cycadales downward the opening mechanism ot the 

 sporangiura is of the nature of an annulus and is epidermal in its 

 origin. 



The facts summarized under the foregoing headings justify the 

 Separation of reproductire mechanisms in the vascular plants into 

 two types: the ectokinetic and endokinetic. The former condition is 

 represented by the annulus and is characteristic of lower forms; 

 the latter is found in the fiber layer, derived from the fibrovascular 

 tissues (particularl}'- modified transfusion elements), and is present 

 characteristically in the microsporangia of existing seed plants 

 (exclusive ofthe Cycadales). Jongmans. 



Weatherwax, F., Morphologv of the flowers oi Zea Mays. 

 (Bull. Torrev Botan. Club. XLIII. p. 127—144. 4 Textfig. PI. 5, 6. 

 1916.) 



The results of these researches are summarized as follows: 



Normally the maize plant is monoecious. The male spikelet is 

 two-flowered. Each flower has three stamens, two lodicules, and a 

 rudimentary pistil. The female spikelet is two-flowered, but, in most 

 instances, the lower flower is aborted. 



In Country Gentleman sweet corn the lower flower of the female 

 spikelet regularly functions the same as the upper one. This same 

 phenomenon has been noted in some spikelets of pod corn. 



The Upper female flower has a pistil and three rudimentary 

 stamens but no lodicules. The lower female flower has a pistil, three 

 rudimentary stamens, and two rudimental lodicules, whether the 

 flower be aborted or functional. 



Structurally and functionally the silk is a Stigma. Pollination is 

 effected by gravity and the wind. A relatively large amount of 

 pollen is procluced. Gross pollination is the m^ore common occur- 

 rence, but self-pollination is possible and occurs to a certain extent. 



In flowers of either sex the rudimentary organs of the opposite 

 sex may be replaced by organs of normal appearance. In many 

 instances these are not functional, but pistils are regularly functional 

 in the tasseis uf some varieties of pod corn. 



E.xcept in pod corn the glumes do not enclose the caryopsis as 

 in most grasses. Jongmans. 



Backhonse, W. O., Note on the inheritanceof„Crossa- 

 bility". (Journ. of Genetics. VI. p. 91—94. 1917.) 

 The object of this note is to show that deductions as to rela- 



