Chapter II — 35 — Sarracenia 



soils is acid, though not always. Wherry found bog water to be 

 sometimes alkahne, though the sphagnum hummocks would contain 

 acid water. Generally he found that when growing in acid water, 

 the pitcher fluid was acid, but not always in the same degree. But 

 occasionally the fluid would be alkaline or neutral. On the same 

 plant the fluid of a young pitcher might be alkaline, and of old pitchers 

 acid — this for Sarracenia purpurea. Hepburn et al. found for some 

 southern species acidity and alkalinity about equally distributed for S. 

 Drummondii and S. Sledgei. Five pitchers of S. flava all held acid fluid. 



Hepburn and St. John examined the bacterial content of closed 

 and open pitchers. Closed pitchers were always sterile. The fluid 

 of open pitchers which had captured prey always contained bacteria, 

 as is to be expected, and these always digested several different sub- 

 stances. The interesting fact is pointed out, however, that these 

 "bacteria digested the proteins so slowly that their part in the di- 

 gestion of prey must be a minor one in the genus Sarracenia, the 

 protease of the pitcher liquor playing the leading role." "The bac- 

 teria apparently live in symbiosis with the Sarracenias, drawing their 

 nutriment from the digested insects, and aiding, to a certain extent, 

 in the digestion of the prey." An exception must be made for Dar- 

 lingtonia where there is no digestion by the pitcher fluid proper (see 

 beyond). Reference is made to the odors of putridity and of am- 

 monia and amines noticed when such bacteria are active. 



The earHer observations of others that water is absorbed was 

 verified, and it was further found that, when nitrogenous substances 

 in solution were used, the absorption of the solutes proceeded more 

 rapidly than that of the water. In the presence of a phosphate buffer, 

 the nitrogenous compound would be absorbed while the total amount 

 of water increased. When a neutral phosphate solution was used, 

 the absorption of the phosphate was less rapid than that of the water. 

 The percentage of compound absorbed usually increased with the 

 length of the period of absorption. The actual entrance of substances 

 into the tissues was demonstrated by the presence of the lithium ion, 

 after introducing lithium citrate into the pitcher fluid. It is thus 

 indicated that the products of proteolysis and phosphates are ab- 

 sorbed by the walls of the pitcher and utilized by the plant. Data 

 on the chemical composition of the tissues are also furnished, but 

 are of only secondary interest here. 



This brief summary of the work of Hepburn and his colleagues, 

 it is gratifying to record, has furnished a comprehensive view of the 

 physiology of the pitchers of Sarracenia in its relation to digestion, 

 which might have remained unwritten but for their evident enthusiasm 

 and dihgence. 



Animals which live in the pitchers of Sarracenia and Darlingtonia. — 

 It is a matter of common observation that the pitcher plants attract 

 a horde of insects of all kinds: "ants, wasps, bees, butterflies and 

 moths" by their nectar, and other forms (beetles, spiders) for other 

 reasons. Spiders frequent the opening of the pitcher in the not vain 

 hope of visits of small insects which may be caught by them. Ed- 

 wards observed this in Darlingtonia. They occur on Drosera, Byblis, 

 Nepenthes and probably others for the same reasons. Minute wasp- 



