50 
Farmer, — On Isoetes lacustris , L. 
Hepaticae, and it reaches its highest expression in forms like 
Dendroceros , in which there is a distinct resemblance to Isoetes. 
Of course, the sporangia of the Marattiaceae naturally suggest 
the explanation that the trabeculae represent the sporangial 
walls, but the inspection of a tangential section through a half- 
matured sporangium, especially of a micro-sporangium, tends 
to weaken the value of such a comparison. In any case, how- 
ever, it must of course be admitted, that if Isoetes is actually 
allied, as I am convinced it is, with the Eusporangiate Ferns, 
the exceedingly common occurrence in them of numerous 
sporangia in close proximity would offer a contrast to Isoetes 
with its single sporangium. Such divisions in the sporangium 
as are formed by the trabeculae are not unknown in Phanero- 
gams — in certain Onagraceae, for example — but I cannot 
regard this fact as in any way tending to establish the multi- 
locular nature of the body in Isoetes. 
The Root . — As regards the root, hardly two writers agree in 
their accounts of its structure and development. The facts 
that its apex ceases at an early age to remain in the meris- 
matic condition, and also that the dichotomy of the apex 
takes place repeatedly while it is still enclosed in the original 
root-cap, serve to render the task of understanding its structure 
one of considerable difficulty. 
Hofmeister, as is well known, regarded its growth as taking 
place by means of an apical cell, and Naegeli and Leitgeb 
also assumed its presence, although on negative rather than 
positive grounds. It is difficult to see how they missed the 
more correct explanation : their figures are extremely good, 
and they actually succeeded in unravelling some of the more 
difficult points, one of which, the nature of the plerome-initial, 
it is not easy to reconcile with any apical cell hypothesis such 
as they put forward : ‘ Der Cambiumcylinder ist anfangs 
immer einzelligV Bruchmann 2 , who studied the root in 
detail, believed he had succeeded in demonstrating three 
1 Naegeli u. Leitgeb, Enst. u. Wachst. d. Wurzeln, Beitr. z. wiss. Bot. 4. Heft, 
p. 134. 
2 Bruchmann, Ueber Anlage u. Wachst. d. Wurzeln bei Lycopod. u. Isoetes , Jen. 
Zeitsch. fiir Naturwiss. VIII. 1874. 
