208 SYSTEMATIC POSITION OF MITRASTEMON. 



in a very few cases, very primitive ducts, annular or spiral, within the 

 tracheidal group. I could not discover any true well-formed ducts. Neither 

 sieve-tubes, nor companion cells, nor bast fibres, nor wood-fibres are found 

 anywhere. There are one or two collenchymatous rather rounded rectangular 

 cells near the bundles. The whole tissue like the host itself contains a 

 considerable amount of tannin. The structure of the peduncles is, upon the 

 whole, quite similar to that of Cytinus, differing from it only in that it 

 lacks well-formed pitted or annular ducts. 



IV. Systematic Position of Mitrastemon. 



As is stated above, Mitrastemon bears a close affinity to plants at 

 present referred to the Rafflesiacese and especially to those of the Apod a n- 

 theae, a tribe of the same family. It also resembles in some respects the 

 Nepenthaceso, Hydonoracese, Aristolochiacese and Balanophora- 

 cess (MAKING n., p. 253). It comes near the Nepenthacese (WuNSCH- 

 MANN) in having single perianth and superior ovary; but greatly differs 

 from it in having peculiar parasitic organs, united stamens, one-celled ovary 

 with many parietal placentas and gamophyllous perianth. It resembles the 

 Hydonoracese (SoLMS-LAUBACH V.) in its parasitism, its leafless, one- 

 flowered-peduncles, but differs in having united stamens, one-celled ovary 

 with many parietal placentas and berry-form fruit. Its affinity to the 

 Aristolochiacese (SOEEREDEB) is to be seen in the gamophyllous perianth, 

 one-celled ovary, berry-form fruit and short columnar styles ; but it is quite 

 distinct in its parasitism, leafless peduncles and united stamens. It some- 

 what resembles the Balanophoracese (ENGLEB) in having a parasitic 

 habit, and scaly leafless flower-stalk ; but the difference in floral structure is 

 so great that it hardly needs pointing out. 



As we have seen in external as well as the internal morphological 

 characters, Mitrastemon has a close relation to the Rafflesiacese, in its 

 absorption-organ, uniflowered leafless peduncles, tetramerous perianth, one- 

 celled ovary with parietal placentas, short columnar style and stigma, and 

 in the structure of its ovules. The only points which formerly led us to 



