Fossombronia longiseta , A ust. 91 
develop from lateral segments as described by Leitgeb 1 for F. pusilla. 
The apical growth of the species was carefully worked out by him, and 
it agrees in all essential particulars with that of F . longiseta. 
Along the ventral surface, just behind the growing point, certain cells 
resulting from the divisions of the primary or inner segment of the apical 
cell, elongate to form glandular hairs. As a rule these are void of chloro- 
phyll, but contain numerous oil-bodies. However, a very few have been 
noticed in which a few chlorophyll-bodies were present, though in a state 
of disintegration. 
The first rhizoid, as a rule, appears rather late in the development 
of the young plant, though in Fig. 1, B and Fig. 4, G it is seen arising from 
the third cell. In a single instance it was seen to develop from the first or 
basal cell. It appears as a delicate, thin-walled, almost colourless structure, 
usually containing one or more granules and oil-globules. In one instance 
a number of chlorophyll-bodies were present. Young plants grown in 
water-cultures produced rhizoids quite as freely as those growing on soil, 
which fact suggests that after all the rhizoid may be other than an organ of 
mere attachment. To be sure it may be said that in the appearance of 
rhizoids on plants grown in water-cultures we have nothing more than the 
manifestation of the hereditary tendency of the plants to develop rhizoids. 
We are not certain that such a tendency is an actual fact, and until further 
and more conclusive light has been thrown upon this subject it will be 
unsafe to say positively what is the function of a rhizoid. Of the fact that 
it serves as a hold-fast we are certain, and the writer has found that stimula- 
tion due to continued contact has led to a more or less extensive branching 
of rhizoids in Anenra and Cephalozia. 
The growing rhizoid of Fossombronia , not unlike the root-hairs of 
higher plants, contains protoplasm in contact with the inner surface of the 
rhizoid wall, and it would appear from this that there must be osmotic 
interchange between rhizoid and the outside medium. Peirce 2 considers the 
rhizoid as the physiological equivalent of the root-hair, hence an absorbing 
organ. Whether or not it is such can be demonstrated only after further 
experimentation and study. 
It is an interesting fact that, so far as the writer’s observations go, the 
earlier rhizoids are quite colourless, the characteristic vinous-purple rhizoids 
appearing after one or more pairs of leaves have developed. In a few 
instances young rhizoids, 50 to 70/x in length, have been observed, con- 
taining along with oil-globules some chlorophyll, which later breaks down 
and disappears. These could not possibly have been glandular hairs, as 
the vinous-purple colour was already present. Very likely the chloro- 
phyll had migrated into the rhizoid from the basal cell previous to the 
formation of the separating wall. 
1 loc. cit. 
3 Peirce (’ 03 ), p. 1 1 5. 
