Francis E. Lloyd —124— Carnivorous Plants 



cells which come to the surface at the base of the gland are epidermic. 

 They are narrower and longer than the others, which are of parenchy- 

 matous origin. The inclosed mass of reticulated, and annular and 

 spiral vessels are obviously an extension of the leaf vascular tissue 

 (j^_4_6). The developmental behavior of the gland in Drosera cor- 

 responds point for point with that of Drosophyllum (Fenner). 



Functions of gland parts. — Such a complicated gland as above de- 

 scribed can scarcely be a simple matter physiologically. The reception 

 and transmission of stimuli, the secretion of mucilage, of one or more 

 ferments, probably of an odoriferous principle, water, and in the op- 

 posed direction, the absorption of the products of digestion are car- 

 ried on. Is it possible to assign any degree of specialization to the 

 various elements of structure? Homes (19296), having studied with 

 meticulous care the behavior of the cells in the matter of aggregation, 

 assigned to the outer layer, the epidermis, the function of "responding 

 directly to the necessities of secretion by the variation of its vacuome". 

 Its cells elaborate the substance secreted. That of the second layer is 

 the regulation of osmotic pressure. The third layer, the parenchyma 

 bell, takes no part in secretion (Homes, 1929^), p. 49). It may be as- 

 sumed, of course, that the cells of the bell allow the rapid transfer of 

 water from the inclosed xylem, but whether the movement is a one- 

 way one only, as Goebel suggested, or not, is difificult to say. 



Reference has been made above to Haberlandt's view that the 

 protoplasmic processes lying between the buttresses of the epidermal 

 cells are sensitive organs, analogous to those seen by him_ in tendrils 

 and other plant parts. Konopka preferred another suggestion in 1930, 

 that the increased surface due to crenellation may be important also 

 in secretion and absorption, as a secondary advantage. Goebel has 

 regarded them in this way. 



With respect to other parts of the gland Konopka has made some 

 further suggestions. The xylem bundle mass is, he says, composed of 

 spiral vessels of narrower bore in the central part, with wider lumened 

 tracheids surrounding them, and the more central vessels widen 

 in contact with the apical portion of the gland. The central vessels 

 are indeed often narrower than the outer, but other details it is diffi- 

 cult to accede. Konopka would attribute different functions to the 

 two regions, but beyond this regards the whole as a water storage 

 organ, which rather obviously it seems to be. He has, however, ex- 

 amined the behavior of the nuclei, and finds that during digestion and 

 absorption there occur changes in them which he interprets as con- 

 nected with taking up and transmitting nutrients from the outer tis- 

 sues of the gland to the stalk cells. He asserts that the nuclei of the 

 endodermis, of the xylem and of the stalk cells, show a gradient of such 

 changes, the nuclei of the more superficial tissues showing greater 

 changes in a quantitative sense than those of the deeper and more 

 removed tissues. To the endodermis (parenchyma bell) he attributes 

 the special function of a protective filter. It must be questioned 

 whether Konopka has advanced sufficient evidence to support this 

 hypothesis. Aside from the nuclear changes claimed to occur by 

 Konopka, there is no other change such as characterizes the secretion 

 cells, namely aggregation (Homes), during periods of activity. This 



