of some Phanerogamic Parasites. 309 
case, however. There the parenchyma-cells are killed and 
their contents entirely absorbed by the haustorial cell. 
It is worthy of note that the papillate epidermal cells 
composing the cushion overlying the young haustorium, which 
make the first opening into the host, and the cells forming the 
sucker of the haustorium, have nuclei even larger than those of 
the majority of active cells in the parasite. Furthermore these 
nuclei are always situated near the tips of the cushion and 
sucker cells, where of course the activity of the cells is greatest. 
Even after a complete union has been affected by the 
conducting tissues of the haustorium with one or two of the 
fibro-vascular bundles in the host, the cells which compose 
the sucker often continue to grow for some distance into the 
pith-parenchyma. Some of these which have penetrated 
deepest into the pith, having dissolved all the starch and 
other contents of the cells into which they have grown, seem 
at last to reach their limit of growth. Their tips enlarge 
until their walls become applied to the walls of the parenchyma- 
cells in which they have buried themselves. If these paren- 
chyma-cells be large the effect is curious. A long sucking-cell, 
retaining a uniform diameter till it reaches the last cell into 
which it penetrates, becomes abruptly larger, blown out like 
a bladder against the walls which confine it. One cannot 
suppose that these enlarged tips are for the purpose of anchoring 
the haustorium firmly in the tissues of the host, for they are 
not formed until the haustorium has been for some time 
imbedded in the host, when the need of such anchoring, if 
there ever was any, has passed. They seem simply the final 
effort of the cells which form them to secure food in a com- 
paratively innutritious pith. 
A comparison of the growth of the haustorium of C. americana 
in the tissues of leaf and stem with what has just been described, 
shows that it penetrates its host in essentially the same way. 
In leaves where the mesophyll consists of large cells, one finds 
the cells of the sucker growing through mesophyll-cells which 
continue to live. The stems of the hosts examined contain 
little chlorophyll, and in them the haustorial cells kill those 
