204 SYSTEMATIC POSITION OF MITRASTE1ION. 



become very much finer until at last the thread consists of a single row of 

 cells, which is called by SOLMS-LAUBACH a rnycerium-thread, on account of 

 its resemblance to a fungus-hypha (SOLMS-LAUBACH II., GOEBEL I., p. 435). 

 Accordingly in every cross section of a region in or near the place where a 

 flower-peduncle stands, we shall invariably find in the bast a number 

 (30-50) of rounded points, each distinct and remote, or sometimes coming 

 into contact and uniting, every one of which is a cross section of a horizontal 

 thread, arranged in a ring or two all round the xylem. Each of these points 

 throws a perpendicular thread through the cambium layer and xylem, along a 

 medullary ray towards the center. The surface view of the network of 

 horizontal threads in the bast is clearly and easily observable with the 

 naked eye in the process of removing the outer parts of the secondary bast. 

 Therefore, the intramatrical tissue in the bast forms a cylinder-like body 

 made of reticulated threads, which completely surrounds the xylem outside 

 the cambium layer. It is justly comparable in some respects to that of 

 Cytlnus which lies in the bast as a true, perfect, but unreticulated cylinder 

 inside the cambium layer. The thallus of Mitrastemon bears even more 

 resemblance to that of Eurgmansia (SoLMS-LAUBACH, IV.) and Pylostylis 

 (SoLMS-LAUBACH II., LoTSY p. 882). Such a structure of the intramatrical 

 tissue is considered, at the present time, to be a character peculiar to the 

 Rafflesiacese and never observed in any other family. The only connec- 

 tion of this tissue to one of another kind which we call a " senker," is to 

 be found in Arceuthobium Oxycedri, a plant belonging to the Loran- 

 thacese (GOEBEL II., p. 379). The perpendicular threads are by no means 

 terete like the horizontal, but are laterally compressed. Accordingly in the 

 cross section of a vertical thread, which is obtainable in a tangential section 

 of the host-root, it comes into view as a lentiform group of cells always 

 laying side by side with a medullary ray, or sometimes laying in a group of 

 bast cells. It is broader and thicker towards the base (i. e. the bast), but 

 narrower and thinner towards the center of the xylem, and at last becomes 

 a thread consisting towards the apex of a single row of cells. 



Therefore, in a longitudinal section of the host-root, and also in a cross 

 section of the same, the vertical threads always appear in the shape of an 



