210 Biologie. — Morphologie etc. 



Le Goc, M. G., Effect of Foreign Pollination in Cycas 

 Rumphii. (Ann. Roy. Bot. Gard. Peradenya. VI. 3. p. 187—194. 

 June 1917.) 



Cycas Rumphii is said to be a native of the low-country oi 

 Ceylon. In cultivation it is propagated by means of adventitious 

 shoots. No seeds are to be found , although extensive search has 

 been made. During this search it was observed that in some areas, 

 in districts where no male plant of any Cycad could be formed, 

 the ovules were always aborted; but in other areas, in localities 

 where male cones even of different genera occur, the ovules 

 obtained a normal size but having no embryo would not germinate. 

 As a result of this discovery, an effort was made to obtain male 

 cones of Cycas Rumphii with a view to making cross pollination 

 experiments, but without success, none were to be found. 



Examination of the füll grown ovules showed that pollen- 

 grains belonging, either to Encephalartos or Macrosanna, had found 

 their way to the pollen Chambers of the ovules and that they had 

 germinated and that the male gametophytes had penetrated the 

 nucellus and although incapable of true fertilisation had stimulated 

 the growth of the ovule. M. N. Owen (Kew). 



Srnall, J., Wind Dispersal Apparatus. (Proc. Linn. Soc. p. 5— 6. 

 Lond. 1916—1917.) 



The purpose of the apparatus is to determine the exact velocity 

 of the wind required to blow the fruits of the Compositae a sufncient 

 distance to ensure proper dispersal. The apparatus consists of an 

 electric fan, a long, wide glass tube, and an anemometer. The tube 

 is moved away from the fan until the fruits are no longer blown 

 right through: the wind pressure at this point is taken as the 

 minimum required for the dispersal of the fruit. Theresults attained 

 with seven species are given in detail. 



Agnes Arber (Cambridge). 



Mc Clatehie, Isabel, „Observation on the Root System of 

 Impatiens Roylei Walfs." (Journ. Linn. Soc. XLIII. N° 294. p. 493 

 May 1917.) 



The primary root System of this troublesome weed is of the 

 normal dicotyledonous type but because of its great power of 

 forming adventitions roots Impatiens Roylei becomes worthy of 

 special consideration. 



This development of adventitious roots, although very irregulär 

 is to a great extent dependent upon certain peculiarities of indi- 

 vidual plants. Should the main axis become curved adventitious 

 roots will develop on the under surface; they are inevitably the 

 result of injury appearing just above the wound but they also 

 frequently appear on robust lateral branches. 



A damp atmosphere is very favourable to their production. 



The position of aerial roots necessarily renders them short 

 and stunted and they soon become protected by a layer of cork, 

 but should they become surrounded by soil they would develop 

 freely. 



Miss Mc Clatehie describes a number of her experiments on 

 seedlings and older plants. She also gives details of the anatomical 

 strueture of the rootsystem describing the development of rootlets 



