IRON COMPOUNDS IN ANIMAL AND VEGETABLE CELLS. 253 
was found to be localised in spherical elements of 16m dia- 
meter, corresponding to the nuclei of the zoogonidia. I have, 
since that date, investigated the cytological character of this 
organism, and have found that though there are, as Fisch,! 
Wager,’ and others have observed, nuclei in the mycelia and 
in the gonidia, the whole of the protoplasm, except in the 
mature gonidia, is chromophilous, that is, it contains chro- 
matin. ‘The nuclei are, indeed, of the more regular form in 
the mature gonidia, but in the mycelia amongst the cells of 
the host (Capsella bursa-pastoris) they are chiefly, if not 
wholly, small masses of chromatin, like those forming the 
‘“nucleoli” in the abjointing gonidia. I have not succeeded 
in finding the mitotic phase either in the mycelia or in the 
developing gonidia, although I have carefully looked for such 
in a large number of preparations. 
The disposition of the assimilated iron corresponds closely 
with the distribution of the chromophilous substance in this 
form. The cytoplasm of the haustoria and of the mycelia 
gave a marked reaction for iron in all the methods of demon- 
stration.2 The mycelial membrane gave no evidence of the 
presence of the element. The small masses of chromatin were 
found to be rich in organic iron. In the terminal enlarged, 
sometimes club-shaped, sometimes truncated, portion of each 
hypha the iron was found to be in a localised as well as in a 
diffuse form. The “nucleoli”? gave abundant evidence of its 
presence, these structures thus appearing in marked contrast 
with the remaining portions of the nucleus, which contain 
relatively less iron than the surrounding cytoplasm in this 
stage. In the subsequent development of the abjointed gonidia, 
the nuclei appear to take up from the cytoplasm all, or nearly 
1 “Ueber das Verhalten der Zellkernein fusionirenden Pilzzellen,” ‘ Ver- 
sammlung deutscher Naturforscher und Aerzte in Strassburg,’ 1885. This 
paper I have not seen, and the only references to it that I can find are those 
made by Wager and Dangeard (‘Comptes Rendus,’ cxi, 1890, p. 882). 
 “ Observations on the Structure of Cystopus candidus,” ‘Rep. Brit. 
Ass. for the Adv. of Science,’ 1892, p. 777. 
3 The material was hardened in alcohol, which was renewed until every 
trace of chlorophyll was removed from the tissues. 
