140 Jeffrey. — Infranodal Organs in 
notes that the infranodal tubercles occurred on the medullary- 
casts in subterranean parts of Calamites, and gradually dis- 
appeared as the stem passed above the surface of the soil. 
The subterranean position of the infranodal organs probably 
suggested to M. Renault their relation to roots. In a recent 
account 1 of the casts of Calamites, Grand’ Eury has described 
more fully the distribution of the infranodal tubercles. He 
states that they are absent on the horizontal rhizomes, 
although these are abundantly provided with roots, and that 
they occur only on the ascending portions of the subterranean 
stems of Calamites. It is apparent from these recent observa- 
tions that there is no necessary relation between the presence 
of roots and the occurrence of infranodal tubercles. It follows 
from the various data introduced in this paragraph that the 
infranodal organs of Calamites were not rhizophorous, and 
further, that, as a consequence, they were not radiciferous 
branches. Hence they do not supply an argument for the 
inversion of figures representing tangential sections through 
the secondary wood of Calamites. 
Convinced by the study of the fossils that the infranodal 
organs of Williamson were not to be explained as the equi- 
valents of the rhizophoric branches of the Equiseta, the writer 
has still felt that it was improbable that they should be 
without analogues in living plants. He has devoted his 
attention particularly to marsh-plants with fistular medullary 
cavities separated by diaphragms, with a large number of 
leaf-traces passing off in the region of the nodes, and with 
considerable secondary wood. The result has been the dis- 
covery of structures which appear to differ in no important 
respect from the infranodal canals (lenticular organs) of 
Williamson. Some account of these is given in the following 
paragraphs. 
II. 
Potentilla palustris is a plant which is particularly character- 
istic in respect to infranodal organs. Photograph 3, PI. VIII, 
1 Foret Fossile de Calamites Suckowii, Comptes Rendus, 1897. 
