ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 213 



depressions of the leaves, but physical methods were devised which 

 showed that the exuded water was not a secretion from a gland in the 

 leaf -tip. All the experiments prove that there is no special tissue 

 which can be regarded as a gland ; neither is there any membrane 

 between the water-channels and the depressions for filtering water. All 

 the structures indicate that " cells lower down in the plant are re- 

 sponsible for the secretion or filtration of water, and there seems no 

 evidence for the existence of special cells for this function outside the 

 root." S. G. 



Reproductive. 



Reproductive Organs and Phylogeny of the Amentales. — P. 

 VuiLLEMiN {Ann. Sci. ISfat. {Bot), 1919, ser. x., 1, 139-200, 3 figs.). 

 An account of the reproductive organs of the Amentales, with special 

 reference to their bearing upon the phylogeny of this group. In 

 describing these organs the author employs the term " amphigonelle," 

 and points out that while a true inflorescence has numerous mono- 

 centric axes, the amphigonelle has a single polycentric axis. Like 

 the pedicel, the polycentric axis arises in the axil of a leaf, which may be 

 unmodified, or bract-like, or elongated into a leafy stem ; in the first 

 case the axillary shoot is entirely reproductive, and in the other cases it 

 is partly vegetative and partly reproductive. The amphigonelle 

 may resemble a capitulum, a spike, or a glomerulus. In the Cupuliferse 

 the axis is oligocentric, being sometimes a true stem with typical vegeta- 

 tive leaves, as in Quercus and Fagus, in other cases functioning as a 

 peduncle ; while the reproductive organs resemble an inflorescence in 

 which a vegetative shoot is subordinated to the reproductive shoots. 

 The amphigonelles enclose sexual organs — unisexual in the lower 

 Amentales, bisexual in the higher types. The primitive male organ is 

 dichotomous, with two filaments and two unilocular anthers, but the 

 dichotomy is gradually suppressed from below upwards, until finally 

 there is a single filament bearing a bilocular anther. The female organs 

 are represented by the nucellus, placentas, and stigmas. No true carpels 

 have been found in the Amentales ; the ovary is of the nature of a leafy 

 emergence surrounding the female organs, tbe partitions corresponding 

 to the outgrowths of the leaf (e.g. the Juglandace^e) or to prolongations 

 of the placenta (e.g. the Casuarinese and Betulaceae). 



The appendages of the amphigonelle are sepals and bracteoles. 

 In the lower groups the sepals are often attached to the stamens or 

 stigmas, while in the higher groups these appendages come into close 

 union with the organs, and become the ovary composed of carpels. In 

 certain female amphigonelles some or all of the bracteoles form a primi- 

 tive cupule ; the latter is well differentiated in the Cupulif er^, but in the 

 lower families of the Myricacese and Juglandaceag it is very rudimentary. 

 In tracing the phylogeny of the Amentales it has not been possible to 

 fix any direct line of descent, but taking into account numerous indica- 

 tions of affinity, we have a system of short branches arising one from 

 another at different angles of divergence. Through the Casuarinese the 

 Amentales are derived directly from the Protosperms, the common 

 source of the Gymnosperms and Angiosperms, themselves derived from 



