1902] CURRENT LITERA TURE 3 1 5 



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the simple type of pitcher seems to result from an early arrest of apical 

 growth and a rapid growth of the central portion of the morphologically upper 

 surface with a consequent bulging out. In the double pitchers, the structure 

 of which is described in detail, the inner pitcher may be supposed to have 

 been formed first, since in the development of the pitchers of Z?. Rafflesiana 

 apical and basal growth in the leaf ceases at an early stage, and the pitcher 

 has assumed a definite form, so that in species with the double pitchers a 

 resumption of apical growth, with the accompanying involution which gives 

 rise to the inner pitcher, can hardly be supposed. As to the function of the 

 pitchers, conclusions based on herbarium material must necessarily be unsat- 

 isfactory. Fairly complete investigations have quite conclusivel)' shown that 

 the pitchers of D. Rafflesiana are to be regarded as living "flowerpots,** con- 

 taining, as they usually do, water and soil and being supplied with a copious 

 root system. In the four species under consideration, all of which are 

 epiphytes, and clearly xerophytic in structure, the author was able to examine 

 the contents of nine pitchers, all of which contained roots, and in all cases 

 more or less soil in the outer but none in the inner pitchers. It seems, as 

 Groom believes to be the case in D. Rafflesiana, that the greater the amount 

 of soil the greater the development of roots in the outer pitcher. That ants 

 bring the soil into the pitchers of these species the author of the paper con- 

 siders certain, the ants making their nests in the pitchers. To what extent 

 the plant depends upon the food material contained in these organs is 

 unknown, but the indications are that they are of no inconsiderable impor- 

 tance. As to the benefit derived by the ants from this symbiotic relation, the 

 pitchers are convenient shelters and nesting places, for which the four species 

 may be assumed to be better adapted than D, Rafflesiana, on account of the 

 narrower entrances and more commodious forms. As to the function of the inner 

 pitcher, they may possibly serve as a place of refuge for the ants in case of 

 danger from drowning. There is some indication, in D, ^ectenoides at least, of 

 a possible function as a feeding ground, the food material being a sweetish 

 substance, evidently a decomposition product. Examination of the inner wall 

 of the outer pitcher reveals the presence of a dense weft of superficial myce- 

 lium, the explanation of the presence of which was impossible. A similarity 

 to forms described by Muller in the " fungus gardens ** of some South American 

 ants was noticed. Dischidia, then, shows a series of modified leaves more 

 remarkable perhaps than any other known genus, the highest specialization 



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of which is found in the four species here described, where the adaptation to 

 the residence of ant colonies as well as the economy of water seems to have 



reached its highest point. — J. Arthur Harris. 



Edgar W. Olive ^^^ has oublished a detailed arrount of the Acrasieae. 



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Monograph of the Acrasieae. Proc. Boston Soc. Nat. Hist. 30: 451-513. phn 



j-5. 1902. 



