Manchester Memoirs, Vol. Ivii. ( 1 9 1 3 ), No. 1 1 . 17 



this for other Uredineae. Similar observations were made 



by Nemec" on the mycorrhiza of Calypogeia, and by 



Groom^^ on that of TJiisniia aseroe. In normal cells of 



the Hollyhock the nucleus contains one or two nucleoli 



and a number of regularly arranged chromatin granules 



united by a network of fine threads {PI. II., Figs. 20 and 



24). When a cell is entered by haustoria the nucleus 



becomes larger and more distinctly visible in the fresh 



material {Pi. /., cf. Figs. 8 and 9), and at a late stage in 



some cases it shrivels somewhat {Pi. I, Fig 11). There 



is a distinct diminution of the chromatin granules, and 



the nucleolus becomes somewhat larger {Pi. II., cf. Figs. 



23 and 24). Groom'*^ has expressed the view that the 



haustoria grow towards the nucleus because it is the 



centre of metabolic activity, but Guttenberg" disputes this 



and holds that the former obtain specific substances, and 



especially chromatin and nuclear sap from the nucleus. 



This he believes explains the shrivelling, as well as the 



disappearance, of chromatin which he records. In the 



present example one of the most striking features is 



the persistence of the nucleus in an unshrivelled condition 



until a very late stage, so it would hardly seem likely 



that the haustoria withdraw the nuclear sap, nor did the 



appearances establish a direct utilisation of the chromatin 



by the fungus, though the amount of chromatin diminished. 



Where an enlargement of the nucleus has been 



observed by previous workers, one of two conclusions 



have been drawn, either that the increase in size points to 



an increase in the metabolic activity of the cell or that 



it is a sign of the approaching death of the cell. In the 



present case, the fact that the chloroplasts aggregate 



^* Beihefle z. Bot. Centralb., Bd. XVI., H. 2, 1904. 

 '^^ Anuais of Botany, Vol. IX., 1S95. 

 ^^ Groom, loc. cit. 

 1 '^ Loc. cit. 



