ZOOLOGY AND BOTANY, MICllOSCOPY, ETC. 63 



dermal sclerenchyrna is interrupted, owing to the activity of a diffuse 

 layer of active cambial cells. Their structure strongly recalls that of the 

 " Staubgrubchen " of the Marattiaceae, and in their mode of formation 

 they resemble ordinary lenticels. The author objects to the term 

 " pneumathodes," proposed by Jost, and proposes to class the lenticular 

 structures found on palm-roots with those found in the Marattiaceae 

 under the name of "primitive lenticels." It is interesting to note 

 the analogy in structure of the respiratory organs of the palms, the 

 ( Jyathacese and the Marattiaceae. 



Extra-floral Nectaries.* — E. Schwendt has studied a large number 

 of genera with special reference to extra-floral nectaries. In the Poly- 

 gonaceae the nectaries are simple epidermal formations, and have no 

 typical secreting tissue. In Oossypium and Tecoma radicans there is an 

 ill-defined secreting tissue. In the Polypodiaceas and in Acacia cornigera, 

 glandular tissue is present but no special secretion, while in the Oleaceae 

 there is a typical secreting tissue, and also a specially modified secreting 

 upper surface. Vascular bundles are specially modified in connection 

 with the more complex nectaries. The nectar-secreting upper surface of 

 the Polygonaceas, etc., and the disk-like nectaries in Tecoma radicans 

 are also trichomes. The secreting hairs of the Polygonaceae begin 

 development by radial division of a single epidermal cell, while in the 

 Oleaceae and Gossypium, the first divisions are tangential. The radial 

 walls of the stalk of the trichomes are suberised just before secretion 

 begins. The nectaries of the Polypodiaoese are of a type hitherto 

 unknown, in that the gland can simultaneously secrete nectar both on 

 the upper and under surface of the lamina. Tannin is so abundant in 

 the nectaries that there is reason for supposing that it has some con- 

 nection with the formation of sugar ; it first makes its appearance while 

 the nectary is still in a meristematic condition. There appears to be 

 good reason for the view that nectaries originated as regulators of the 

 passage of water through the epidermis, i.e. that in the first place they . 

 behaved somewhat like hydathodes. 



Reproductive. 



Polycarpellary Origin of the Pistil of the Lauracese.f — M. 

 Mirande has studied the pistil in the Lauraceaa, and concludes that the 

 present opinion as to its monocarpellary character is erroneous. The 

 investigations in the Cassythaceae clearly show traces of three carpels, 

 the posterior of which is prolonged into a style and stigma, while the 

 two latero-anterior abort. The ovarian canal which opens at the base of 

 the single persistent style, and brings the ovarian cavity into communi- 

 cation with the exterior, is nothing but au incomplete stylar canal which 

 ends at the level where the two anterior carpels are about to expand. 

 Further investigations made upon other groups of the Lauraceaa confirm 

 these results, and hence the author concludes that the pistil of the 

 Lauraeere is composed of several — usually three — open carpels, one 

 posterior, and two latero-anterior. 



* Bot. Centralbl., xxii. (1907) pp. 245-86 (2 pis.). 

 t Comptes Kendus. cxlv. (1907; pp. 570-i!. 



