206 SYSTEJL\TIC POSITION OF MITRASTEMOy. 



Del.vfield^s Hemfitoxyliu solution. 



Wliile the liorizoutal tlu-eads iu tlio bast sends inwards, in cross section 

 of tlie liost-root, one vertical tluead fajwards tlie ceuter, they push outwards 

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

 important fuuction, not eveu of absorption. 



In cross sectious of a remoter part towards the liost-apex, i.e. a region 

 ■where the root is nearly 3-5 mm. iu diameter, wo fiud a thaUus consistiug 

 of single-rowed cells near or in the caml>ium-layer. The cells, the outer-most 

 one esp)ecially, of the thallus of this region are, in almost all cases, com- 

 paratively large, and each, the outermost one esjjecially, contains 2— ± or 

 sometimes as many as eight nuclei. The nuclei ai-e at one time round aud 

 at another dumb-bell-shaped, sometimes cm-ved, fasiform or elougated, and 

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

 others quite large. They are, in my opiuion, as considered from their beiug 

 very variable in sha^De aud size, aud from the ixjsition of their ceEs, ix)ssibly 

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

 are uearly of the same shax^e, as those formed by amitose in the cells of 

 Characese, Tradcscantia (Stkasburger I., p. 77, 11., pp. 24-45), aud in 

 those of a root-bulbulus iufected with a kiud of mycorrhiza (Shibata, p. 644- 

 672). Here, in the pi-esent case, the nuclei take, it scems to me, at fii'st a 

 very inegular amoeboid shai^e, then curve and fold, at last contract at the 

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

 thiLs formed seemed to liave come into contact and pixabably to liave united 

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

 divide mitosely or whether they have thatability theu first when their union 

 is accomplished, I am not in a jwsition to decidc, uor does tliat question 

 come withiu the piurpose of the preseut paper. It is quite probable, how- 

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

 nourisluuent, just as is seeu in the cells of endosi>erma aud those of a root- 

 Ijulbulus infected with a kind of mycorrhiza (Strasburger 1. c, Shibata 1. c). 



On comparing the tissue of the infected host-ixx)ts witli that of im- 

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

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



