598 SUMMARY OF GUERENT RESEARCHES RELATING TO 



upon its systematic position. The author considers that it should be 

 regarded as a distinct genus belonging to the Abietinaj, and supports 

 this view on the following characters : 1. The cones are erect, with per- 

 sistent scales, the latter being separate from the bract nearly to the base ; 

 there is a single megaspore mother-cell. 2. The staminate cones are in 

 clusters on fertile branches with two abaxial microsporaniiia on each 

 sporophyll ; the pollen is winged. 3. The pollen when shed consists 

 of two polar cells, an antheridial cell and the tube-nucleus. 4. There 

 are no resin-ducts in the secondary wood except as the result of w^ounds; 

 ray-tracheids are never formed. 5. There is a large cotyledonary tube, 

 a fact of significance in connexion with theories of polycotyledony. 

 (5. The central axis is prolonged into the primary root. 7. The leaves 

 are spirally arranged and have two vascular strands with two marginal 

 resin-ducts. 8. The sieve-tubes occur in single, interrupted rows, with 

 plates on the terminals ; there is protoplasmic connexion through the 

 small perforations of the plates. 



Leaf Nectaries of G-ossypium.* — E. L. Eeed describes the glands 

 found on the midrib, and sometimes on the other principal veins of the 

 underside of the leaves of Gossypium hirsutum. Tiiese glands are 

 " oval-shaped depressions, filled with closely-crowded multicellular 

 papillge and surrounded by a thick wall of epidermal cells." The 

 papillse arise from epidermal cells which cease to develop normally, but 

 divide so as to form short pedestals ; the numerous divisions which take 

 place before the papillis are fully formed are strongly reminiscent of the 

 development of the antheridia in Riccia. 



Wounding and Regeneration of Plants. t — L. Daniel publishes the 

 results of further investigations as to the effects produced by wounding 

 different parts of a plant. The first series of experiments was made 

 upon the adult form of Eucalyptus glohosus, and as a result of decapi- 

 tation those portions of the tree which replaced the branches which had 

 been removed resumed the juvenile form for several mouths. The 

 author believes that this is the first instance of the kind to be recorded, 

 but that such cases will prove to be by no means uncommon. The 

 second series of experiments deals with the effects produced by cutting 

 growing roots of the common carrot. In some cases portions of the 

 tap-root were removed before tuberization had commenced ; in others 

 the wounds were made subsequent to tuberization, and at some disbfince 

 from the neck. In the first case the cut root formed two branches 

 which were more or less unequal in length, and with greater or less 

 response to geotropism, according to the stage of development when the 

 wounds were made. In the second case the main root ceased to grow 

 and merely he ded, but some of the lateral roots elongated and swelled 

 in an irregular manner. The author is of the opinion that the malformed 

 roots so frequently found by growers are mainly due to wounds made by 

 slugs or other soil-pests during early stages of growth. 



* Bot. Gaz., Ixiii. (1917) pp. 229-31 (2 pis. and 1 fig.). 

 t Rev. G6a. Bot., xxix. (1917) pp. 65-72. 



