1024 SUMMARY OF CURRENT RESEARCHES RELATING TO 



cations sometimes aided by local deposit of pigment or resin, and this 

 modification of structure is due in part to pressure of the external 

 structure upon the formative tissues, and in part to physiological 

 peculiarities of the plant itself independently of such pressure. 



These indications are thus seen to be essentially in accord with 

 the views generally held at the present time. 



6. The influence of meteorological conditions in determining the 

 growth of each season is most important, particularly with reference 

 to rainfall. 



7. Periodicity in rainfall corresponds with periodicity in growth. 



Anatomy of Pitcher-plants.* — MM. E. Heckel and J. Chareyre 

 report the results of an anatomical investigation of various pitcher- 

 plants belonging to the genera Sarracenia, Darlingtonia, and Nepenthes. 



In the pitcher of Sarracenia they distinguish (1) the lid region, of 

 which the upper (exterior) epidermis presents the ordinary leaf sur- 

 face, while the lower surface is formed from cells with sinuous walls, 

 and is fiirnished with very long, rigid, transparent, downward directed 

 hairs. (2) The cells of the very short throat region are rectangular, 

 elongated in the direction of the greatest dimension of the leaf. The 

 cell-walls are thick, and on the external wall there is developed an 

 extremely short, shining, downward directed hair-process. (3) The 

 median region occupies two-thirds or the upper half of the pitcher. 

 It has an epidermis of large cells with sinuous walls and abundant 

 protoplasmic contents, and between its cells there occur numerous 

 glands of eight cells, four triangular central, and four much larger 

 peripheral. (4) The foot of the pitcher is alone assimilative ; it is 

 lined by small epidermic cells with rectilinear walls, some inclosing 

 colouring matter, and all provided with abundant protoplasm. The 

 hairs are very numerous, rigid, coloured, and directed downwards. 

 The cavities of Darlingtonia californica, the only species of that 

 genus examined, are anatomically wholly comparable with this fourth 

 region. 



In Nepenthes (1) the epidermis of both surfaces of the lid has 

 sinuous cells with almost sessile glands, of which the base is formed of 

 a single short cell, and the head of four or five reddish cells, forming 

 a rosette. Delicate multicellular reddish hairs also occur. The 

 other characters are those of the leaf. (2) The throat region forms 

 the upper half of the pitcher below the collar, and is provided with an 

 epidermis of sinuous cells, with abundant protoplasm and distinct 

 nucleus. Many of the cells exhibit a swallow's-nest-shaped cavity, 

 with greyish granular contents, and downward directed opening. 

 The mesophyll layer of this and of the next region exhibits numerous 

 cells with crystals of oxalate of lime, while others more numerous 

 possess a very large nucleus and abundant colourless granules, with 

 active Brownian movement, (3) The epidermal cells of the foot of 

 the pitcher have very thick walls, and the glands are formed from a 

 mass of small somewhat thick-walled cells, with abundant protoplasm 

 and bright red colour. The glands are contained in a nest formed 



* Oompte8 Kendus, ci. (1885) pp. 579-82. 



