33 ^ Groom. — On Thismia Aseroe [Bee cart) 
Origin of Lateral Members on the Vegetative Axis. 
I did not succeed in finding any sufficiently early stages of the 
lateral absorbing organs, but their structure and attachment to 
the main axis suggest that they arise endogenously in that they 
arise from tissue lying deeper than the sheath. The scapes 
develop from cells which lie deeper than the sheath (Fig. 3). 
Beyond making this statement I can say nothing. The very 
young scape could be identified as such by the feeble lobes 
representing the primordia of the scales. Even when the 
scales were clearly differentiated the young buds could be 
seen covered with layers of cells belonging to some external 
tissues. 
Development of the Mycorhizal Mycelium , and the Relations 
between it and the Nuclei of the Infected Cells of Thismia. 
In view of the all-important functions ascribed to the 
nucleus of a cell, the question naturally arises as to the 
relation between the nucleus of the host-cell and the hyphae 
of the symbiotic Fungus. If the host-cells and the fungal 
hyphae do actually work in harmony, and if the nucleus be 
the guiding centre of a cell, we should expect that some 
intimate relations would exist between the host’s nuclei and 
the guest’s hyphae, and that possibly such relations would be 
reflected in the histological details of the symbionts. In the 
thallus of Thismia the coarseness of the hyphae, and their 
long persistence as distinct filaments, render investigation of 
this question simple. 
The mycorhizal hyphae in the different layers of the thallus 
of Thismia may be traced to the apex as separate living 
hyphae which reach nearly as far as the dividing merismatic 
cells. The hypha , then> does not enter a cell till the latter has 
finished dividing and already possesses a nucleus clothed with 
a distinct permanent membrane. Tims there is no evidence 
of any exchange of living nuclear material between guest and 
host. My material was not fixed in such a manner as to 
enable me to assert or deny any protoplasmic continuity 
