SYSTEMATIC POSITION OF MITRASTEMON. 203 



SOLMS-LA.UBACH VI.). Fruit baccate, slightly larger than the ovary, and com- 

 parable to that of the Apodanthese. In the case of a plant which was sent 

 from its native locality, and kept growing in a pot in a green-house here in 

 Tokyo, I have observed that the style which at the base is jointed to the 

 ovary is, when the fruit is fully ripe, separated by a slit along the articula- 

 tion. Seeds minute and very numerous, with a hard reticulated testa like 

 those of rafflesiaceous plants. 



III. Inner Morphology of Mitrastemon y especially 

 with regards to its systematic Position, 



1. Anatomy of the intramatrical Tissue. 



The intramatrical tissue of the parasite in the host root is entirely of 

 the kind generally called a " thallus " wliich, in its main parts, exists in 

 the bast of the host root. It is a formless mass just under the peduncle of 

 a flower in the bast and soon separates into a number of threads running 

 right and left along the long axis of the host root ; anastomosing with each 

 other, and forming a network which completely surrounds the host-root in 

 the middle layer of the bast and on the outer side of the cambium layer. 

 Flower peduncles are generally found most profusely on roots 1 cm. or more 

 in diameter. From each thread of the network-thallus a number of smaller 

 threads much finer than the preceding are sent out perpendicular to it 

 towards the center of the xylem. For convenience sake, I shall call a 

 thallus-thread running horizontally along the long axis of the root in the 

 bast-region a horizontal thread, and one running vertically towards the center 

 of the xylem a vertical thread. The horizontal threads in the bast are com- 

 posed, as is seen in a cross section of the host root, of rounded plasmatic 

 cells in the periphery, but of a elongated ones towards the center, and in 

 most cases there are found near the center some tracheids with spiral 

 markings. The peripheral plasmatic cells, it seems to me, are comparable 

 to the phlom of highly organized plants in their function, while the central 

 somewhat elongated tracheidal cells resemble the xylem of the same in their 

 function. Towards their ends, the threads, both vertical and horizontal, 



