INSECTIVOROUS PLANTS. 15 1 



In 1899, Clautriau published a very inteiesting paper on digestion in the pitchers of 

 Nepenthes. He began his work on plants of Nepenthes melamphora in their natural habitat 

 in the forest of Tjibodas on Mount Gedah, one of the volcanoes of Java. The following 

 is an abstract: 



Nepenthes melamphora is very abundant at an altitude of 1,500 to 2,200 meters, where the 

 temperature is moderate, never exceeding 18 to 28 degrees at midday. Under these conditions 

 digestion was much retarded. 



He found that the use of cooked egg-albumen introduced bacteria and fungi. To avoid this 

 source of error he diluted egg-albumen with 9 times its volume of distilled water, filtered it, and 

 rendered it incoagulable by the addition of o.i mg. of crystallized iron sulphate per 100 cc., or i mg. 

 in case of eggs not perfectly fresh. This liquid could be sterilized by boiling and introduced into the 

 unopened pitcher under absolutely aseptic conditions, and also formed the basis for an exact com- 

 parison of the quantity of albumen digested in various experiments. As it kept indefinitely the 

 same mixture could be used throughout. The iron sulphate used did not exert an injurious effect 

 either on the pitcher liquid or the tissues of the pitcher itself. To render this fluid coagulable it is 

 only necessary to add a little of an alkaline salt and to acidify very slightly. 



As to the quantity of insect remains in the pitchers, Clautriau's observations led him to conclude 

 that this depends on the abundance of insects in the locality in question. He found the pitcher 

 liquid colorless, slightly viscid, insipid in taste, but with a slight odor, reminding one of certain honey, 

 especially when the liquid contained insects. As the result of a great many observations he always 

 found in unstimulated pitchers a litmus neutral liquid. He states that he drank the fluid from a great 

 many unopened pitchers in his ascent of Gountour : " On eut dit une eau un pen mucilagineuse, mais 

 sans le moindre saveur d6sagr6able." Closed pitchers sometimes contained acid liquid, but this was 

 due, he thinks, to a shock of some sort. He was able often to cause acidification in closed pitchers 

 by shaking vigorously, the test for acidity being made the following day. Under natural conditions 

 such stimulation might be caused by the wind, by birds, or by the movements of larvae (mosquito, 

 etc.) which sometimes reach adult form in the liquid. The introduction into the closed urn of any 

 foreign body, even very slender pieces of drawn out glass tubing, provokes the secretion of acid. 



The presence of uninjured larvse in the pitchers does not, he thinks, exclude the presence of an 

 enzym while it does testify to the absence of a toxic or anaesthetic substance. The fact that insects, 

 falling into the liquid, were very slowly killed is another evidence against the presence of a toxin. He 

 found that ants which had been immersed in the liquid half a day, recovered gradually when washed 

 and dried somewhat. The captured animal is finally digested, only the chitinous parts remaining. 

 The liquid remains absolutely limpid and without disagreeable odor, a proof that putrefaction has 

 not taken place. This was also confirmed by use of the microscope. He found it impossible to add 

 antiseptic substances to the fluid inside the pitchers without injuring them, even when these sub- 

 stances (formalin, chloroform, camphor, essence of mentha or citron) were used in extremely minute 

 quantities. It is easy, however, by working aseptically on unopened pitchers to show that digestion 

 takes place in the absence of bacteria and thus disprove the views of Dubois and Tischutkin. 



The multiplication of bacteria in pitcher liquid (when cooked-egg albumen was used) appeared 

 to be dependent on the amount of albumen added. Thus when only a small amount was present 

 absorption by the pitcher kept pace with its digestion, affording unfavorable conditions of nutrition 

 to bacteria. On the other hand, in liquid provided with a large amount of albumen, digestion was 

 more rapid than absorption and bacteria developed rapidly. In no case was he able to obtain 

 complete asepsis with cooked egg albumen. Moreover, much larger quantities of the fluid albumen 

 were digested in a given time than of the coagulated albumen. 



In his experiments with incoagulable albumen, Clautriau endeavored in vain to detect the 

 presence of appreciable amounts of peptone. He found that in some cases the addition of albumen 

 induced an acidity of the liquid corresponding to that of 2 cc. per liter of hydrochloric acid. The 

 liquid became somewhat opalescent at first, later transparent, with an amber tint. Digestion was 

 very rapid, but chemical analysis failed to demonstrate any products of digestion in the liquid though 

 many experiments were made with varying amounts of albumen. When he had waited a sufficient 

 time he also failed to find the original albumen. His conclusion is that the albumen is rapidly modified 

 in the absence of bacteria, and that the products are absorbed as fast as produced. 



He made, also, experiments in vitro to determine whether the r61e of the plant consists simply 

 in the secretion of an acid and a zymase. The liquid from both open and closed pitchers was used. 

 In addition to liquid albumen, one part received a few drops of chloroform, another was heated to 

 100°; the third received no treatment. They were left in the open, beside pitchers which served 

 as controls. No digestion took place in the test-tubes though it was rapid in the controls. In only 

 a single case did he obtain in vitro the disappearance of the albumen (almost complete) and the 



