206 SYSTEMATIC POSITION OF MITRASTEMON. 



Delafieid's Hematoxylin solution. 



While the horizontal tlireads in the bast sends inwards, in cross section 

 of the host-root, one vertical thread towards the center, they push outwards 

 two or three short branches towards the bark ; but they seem to have no 

 important function, not even of absorption. 



In cross sections of a remoter part towards the host-apex, i.e. a region 

 where the root is nearly 3-5 mm. in diameter, we find a thallus consisting 

 of single-rowed ceUs near or in the cambium-layer. The cells, the outer-most 

 one especially, of the thaUus of this region are, in almost all cases, com- 

 paratively large, and each, the outermost one especially, contains 2-4 or 

 sometimes as many as eight nuclei. The nuclei are at one time round and 

 at another dumb-beU-shaped, sometimes curved, fusiform or elongated, and 

 the nuclei in the same cell are of very different sizes, some being small, 

 others quite large. They are, in my opinion, as considered from their being 

 very variable in shape and size, and from the position of their cells, possibly 

 formed, not by indirect, but by direct division. The nuclei just mentioned 

 are nearly of the same shape, as those formed by amitose in the cells of 

 Characese, Tradescantia (Steasbuegee I., p. 77, IL, pp. 24-45), and in 

 those of a root-bulbulus infected with a kind of mycorrhiza (Shibata, p. 644- 

 672), Here, in the present case, the nuclei take, it seems to me, at first a 

 very irregular amoeboid shape, then curve and fold, at last contract at the 

 middle, and divide into two. I have also observed a case where two nuclei 

 thus formed seemed to have come into contact and probably to have united 

 again. Whether nuclei thus divided by amitose division have the ability to 

 divide mitosely or whether they have that ability then first when their union 

 is accomplished, I am not in a position to decide, nor does that question 

 corae within the piu"pose of the present paper. It is quite probable, how- 

 ever, that this amitose division has been caused by the supply of two much 

 nourishment, just as is seen in the cells of endosperma and those of a root- 

 biilbulus infected with a kind of mycorrhiza (Steasbuegee 1. c, Shibata 1. c). 



On comparing the tissue of the infected host-roots with that of un- 

 infected, we find that the secondary bast of the former is usually extremely 

 swollen, and there is no considerable amount of lamellae of depressed sieve 



