448 SUMMARY OF CURRENT RESEARCHES RELATING TO 



laterally upon the leaf-stalks, resembling in colour and structure the 

 original leaf and performing its functions. Winkler finds that in the ma- 

 jority of cases if the blade be removed, two, more rarely one and still more 

 rarely several, lateral outgrowths arise from the wing-like edge of the 

 stalk and form as many new leaf-blades. The new development appears 

 usually 5-6 days after the operation and directly below the cut end of 

 the stalk, wherever the cut has been made. The new blade arises 

 chiefly from the epidermal and subepidermal layer of the petiole ; sub- 

 sequently a procambial strand is formed connecting with the vascular 

 bundle system of the stalk, and forming the conducting tissue of the 

 new leaf-structure. The author finds that similar blade-regeneration 

 ensues in the case of any of the other leaves of the first vegetative 

 period. 



Cork-formation in the Interior of the Leaf-stalk of Nuphar 

 luteum.* — O. Amberg describes the formation of a protective layer of 

 cork in the parenchymatous cells of the leaf-stalk of this water lily 

 as a result of the destruction of tissue by an insect, which had eaten 

 out a great part of the internal tissue, forming hollow chambers com- 

 municating with the outside air by narrow openings. 



Union of Branch and Stem of the same Tree.f — O. Lenecek de- 

 scribes such a union in a pine of about 50 years of age and 20 metres 

 high. The branch springs from just above the base of the main axis 

 and makes rather more than one complete turn round it ; in the lower 

 part the branch is closely flattened to the stem but not coherent with it, 

 but for about 2 metres of its length the two are closely coherent, the 

 branch being imbedded in the cortex of the stem. The free end of the 

 branch was dead. The occurrence is explained by the death of the 

 terminal bud of the young plant, when its place was taken by two 

 lateral branches one of which grew more strongly to form the main axis 

 while the other formed the branch which has become in part coherent 

 with the main axis. The lower portion of the branch showed growth in 

 thickness, which however ceased in the portion united with the stem. 



Reproductive. 



Notes on Living Cycads— The Zamias of Florida.^ — G. E. Wie- 

 land has examined a number of specimens from the Miami region. One 

 is figured, and shows remarkably the disproportion in size between the 

 ovulate cone and the plant on which it is borne, the cone being often 

 much larger than the underground stem on which it is produced. The 

 free branching is al?o well shown ; a male plant is reported with as 

 many as 39 cones ; and when a trunk is cut off below the crown of 

 leaves several new crowns may form. In one of the female cones a 

 pinnule of normal structure had grown out from beneath the tip of one 

 of the upper abortive sporophylls. This recalls the much more striking 

 case of reversion described by Thiselton-Dyer in Encephalartos villosus § 

 and emphasises the statement that the carpophyll is merely a trans- 

 formed foliage leaf and capable of being replaced by it. 



* Vierteljahrsschr. Naturforscli. Ges. Zurich, xlvi. (1902) pp. 326-30 (1 pi.). 

 + Verh. zool.-bnt. Gen. Wien. Hi. (1902) pp. 165-8 (1 fig.). 

 t Amer. Journ. Sci., xiii. (1902) pp. 331-8 (5 figs.). 

 5 See this Journal, ante, p. 65. 



