506 Osborn,— Some Observations on the Tuber of Phylloglossum, 
neighbours in size and shape, hence in the cell mass the ‘ tracheides * are 
more or less isodiametric (Photo 10), while in the dropper they are elongate. 
Within the adventitious cell mass the ‘ tracheides * form a broad core 
Text-fig. 43. Detail of apex of tuber seen Fig. 41. Starchy tissue indicated by heavier 
outline to cells, x 27 o. 
extending towards the original leaf but not reaching so far as sub- 
epidermal tissue, hence, of course, they never form a connexion with the 
leaf trace. In the tuber stalk it is interesting to observe the vascular 
supply may expand to form a cup of ‘ tracheides * around the apex (Text- 
fig. 43), as has been described in the normal tuber. 1 Whilst lignification is 
1 Wernham, H. F. ( 1910 ) : loc. cit. ; p. 388. 
