of some Phanerogamic Parasites . 295 
the cells by the repeated divisions of which the conical 
haustorium increases in length. The haustorium consists of 
these cells and their offspring only, no others from the cortical 
parenchyma or the epidermis contributing at any time to 
its mass. 
By the growth of the haustorium, the cells of the cortical 
parenchyma which immediately overlie it become compressed 
and, pushing outward, form a slight elevation on the surface 
of the stem. Meanwhile the cells of the epidermis covering 
this region of growth and consequent pressure, and those in 
the near vicinity, again begin to grow. Their outer cutinized 
and thickened walls are partially resorbed. These rejuvenated 
epidermal cells grow out into long thin-walled papillae, with 
abundant protoplasmic contents, and large nuclei situated 
near the tips of the cells (see Fig. 4'). In this way a cushion- 
like structure is formed (see Figs. 4 and 5), highest at the 
centre and at the periphery, with a broad shallow depression 
between ; and by the circumnutation of the stem it becomes 
closely applied to the surface of the host. The raised margin 
of the sucker acts more or less as a prehensile organ, as already 
pointed out by Chatin in his description of C. monogyna, Vahl 1 . 
The epidermal cells composing the cushion, being now 
applied to the epidermal cells of the host, exude through 
their thin walls a solvent which attacks and dissolves the walls 
and contents, first of the epidermal, then of the immediately 
underlying cortical cells, of the host. Thus an opening into 
the host is effected. This solvent activity is greater in the 
centre of the cushion, directly over the haustorium, and 
diminishes rapidly towards, and ceases altogether before 
reaching the periphery. During this time the haustorium, 
already nourished perhaps by the dissolved cells of the host, 
grows rapidly, pushes its way by the combined action of 
solution and pressure through the overlying cortical paren- 
chyma and, breaking through and crushing the epidermis 
which covers it, passes into the host through the opening 
1 A. Chatin, Anatomie Comp, des Vegetaux Parasites, Dicotyledones. Paris, 
1857-1862. 
