252 
Birbal Sahni. 
Kew, and of Mr. R. I. Lynch, M.A., Curator of the Cambridge 
Botanic Garden, who helped me with fresh material. To both my 
sincere thanks are due. I have also to thank Mr. Ridley and 
Mr. C. H. Wright for help in identifying the specimen of 
N. volubilis. 
II. Methods. 
Special mention may be made of the way in which the diagrams 
in Text-fig. 4 were obtained. The stele of the primary stolon being 
only loosely attached to the cortex, it is easily dissected out. When 
freshly removed it is cylindrical, but on being left to dry up, it 
assumes the shape of a fluted column of which the ridges correspond 
to the exarch protoxylem strands, and the grooves were filled by the 
now badly shrunken thin-walled phloem and pericycle. On such 
specimens, prepared from regions where the stolon branches, the 
successive bifurcations of the protoxylem strands can be traced with 
ease. 
Text-fig. 1. Nephrolepis volubilis. Photograph (much reduced) of portion 
of primary stolon p (loosely twining) bearing several lateral plants (x). 
Repeatedly coiled stolons are seen at the points of origin of the lateral plants. 
At y, a young stolon which has not yet grasped a support. 
