BROOM-RAPES, BALANOPHOREE, RAFFLESIACEE. 185 
certainty where the epidermis of the nutrient root ceases, and that of the Broom- 
rape begins. The latter looks as if it were a branch growing out of the root it preys 
upon, and this apparent fusion gave some colour to the view of the earlier botanists, 
who, ignorant of the life-history of these parasites, believed that they did not arise 
from seeds, but were pathological outgrowths of the roots, produced from their 
tainted juices; in other words, that they were “pseudomorphs” sprouting from 
diseased roots in the place of leafy branches. 
It is also deserving of mention that some of the thick, fleshy fibres issuing 
laterally from the nodulated seedlings curve towards the host’s root, bury their tips 
in the cortex, and thenceforth behave exactly like the peg which was inserted at the 
point where the seedling first became attached. We must leave undecided the 
questions as to whether the other fibres, which terminate freely in the earth, are 
«capable of taking up food-materials from that source, whether these fibres are only 
present in perennial species and become the starting-points of new individuals, and 
lastly, whether they should be looked upon as root-structures or as stem-structures. 
In addition, it is noteworthy that in many Orobanche® only those embryos 
continue to develop which meet with a plant suitable to be their host. Although it 
is not the case that every species of Orobanche adopts one particular species of 
plant as foster-parent, yet thus much is certain, that most of them only thrive on 
members of a limited circle of species; one lives exclusively on kinds of Wormwood, 
a second on species of Butter-bur, and a third on those of Germander. For 
example, Orobanche Teucrii prevails on Teuerium Chamedrys, Tewervwm mon- 
tanum, &e., the hosts being invariably species of the genus Teueriwm. Suppose a 
hill thickly covered with plants comprising Teucriwm montanwm growing in 
company with thyme, rock-roses, globe-flowers, sedges, and grasses, but no great 
abundance of the Tewcriwm, a plant belonging to the species named occurring only 
here and there, and let Orobanche Teuerii have established itself at one particular 
spot, have attained to flowering and developed fruits, the tiny seeds of which have 
been shaken by the wind out of the ripe capsules. Owing to the exceptional 
minuteness and lightness of its seeds, every gust of wind will scatter them in 
innumerable quantities over the entire hillside and beyond it. The next step is 
germination. Filiform embryos emerge from the seeds, in the manner deseribed 
above, and penetrate into the earth. Teueriwm montanum being only sparsely 
present on the hill in question, comparatively few seedlings will meet with the roots 
of that plant, whereas thousands will fall in with the roots of the thymes, rock- 
roses, globe-flowers, sedges, and grasses. But, curious to relate, only those seedlings 
of Orobanche Teucrii which come into contact with the roots of Teweriwm 
montanum establish themselves firmly, penetrate into them, and continue their 
development; whilst the numerous individuals which touch the roots of the thyme 
and other plants perish. This phenomenon can scarcely be explained in any other 
way than by the supposition that the roots of Teueriwm montanum alone, by 
virtue of their special structure and quality, afford a suitable nutrient substratum, 
and therefore constitute centres of attraction for seedlings of Orobanche Teuerii; 
