Francis E. Lloyd — 102 — Carnivorous Plants 



(Darwin, Goebel, Fenner, Quintanilha). The secretion appears 

 normally when the mucilage glands are stimulated by the catching of 

 prey, but not merely mechanically, as by placing on them sand grains, 

 bits of paper, etc. Fenner showed in considerable detail by appropri- 

 ate experiments that the maximum activity of the sessile glands is ob- 

 tained when, after the stalk glands nearby have received prey, both 

 prey and mucilage secretion are brought into contact with them. But 

 in the presence of mucilage removed from the stalked glands and mixed 

 with the juices of prey, leaving the stalked glands unstimulated, the 

 sessile glands work only slightly if at all. Fenner concluded that the 

 maximum activity of the sessile glands is called forth by something 

 passing through the tissues by way of the vascular elements (phloem). 

 The sessile and stalked glands must, therefore, be considered as a single 

 mechanism in which one part is dependent on the other. 



There is a general agreement on the part of the authors mentioned 

 that Drosophyllum exercises its own proper power of digestion, and that 

 this is not the result of bacterial activity. As mentioned already, 

 Goebel regarded digestion as too rapid for bacterial action, and that the 

 presence of formic acid excludes such activity, and though he was 

 unable to state the concentration of acid present, he supports his in- 

 ference by inoculating nutrient gelatine plates with negative results. 

 The activity of formic acid may not, however, Goebel adds, be con- 

 fined to that of an antiseptic, but it may consist in an initial dis- 

 solution of the proteins of the body of the prey, with the escape of 

 materials v/hich then affect the sessile glands and stimulate them to 

 greater activity. 



Darwln found that fragments of egg albumen, fibrin, were acted 

 upon rapidly when they came in contact with the sessile glands. If 

 only in contact with the stalked glands, they were not attacked. If 

 then placed on the sessile glands, there was a copious secretion, and 

 the albumen was completely dissolved in 7 to 22 hours. "We may 

 therefore conclude, either that the secretion from the tall glands has 

 Httle power of digestion, though strongly acid, or that the amount 

 poured forth from a single gland is insufficient to dissolve a particle of 

 albumen which within the same time would have been dissolved by the 

 secretion from several of the sessile glands." Fibrin likewise, when 

 placed on the stalked glands, was not attacked, though, as in the case 

 of albumen, the secretion was absorbed (together with whatever es- 

 caped into it from the fibrin). But when the fibrin was slipped onto 

 the sessile glands, digestion proceeded rapidly (17 to 21 hours) with an 

 abundant exudation of fluid from the glands. Darwin thought the 

 digestion more rapid than in Drosera. He had not excluded the action 

 of bacteria, which, however, as above said, Goebel did by suitable 

 culture experiments. He observed a more rapid action than did 

 Darwin. A fibrin flock i cm. long and one-fourth the width of the 

 leaf was noticeably attacked in a half-hour on a warm summer day, 

 and in an hour no trace could be seen, though the spot had been care- 

 fuUy marked by a bit of paper. With a lens small fragments could 

 still be seen. A true digestion, he concluded, is therefore present. The 

 enzyme is secreted in response to a special stimulus, and chiefly, if not 

 exclusively, by the sessile glands. The stalked glands are chiefly a 

 trapping apparatus (Goebel 1891). 



