with special Reference to the Mode of Connexion of Cells. 105 



though it is not improbable that even in such cases other threads 

 traversing' the general wall will be found to occur. 



Where both " pit-threads " and " wall- threads " coexist in one and 

 the same cell, the former are stouter and more readily stainable than 

 the latter. In pitted cells the pit-threads are necessarily in groups, 

 and it is a point of some interest that the wall-threads also are 

 usually in groups — as though a pit were present. This is especially 

 striking in such cases as the unpitted cells of Tamus communis 

 (fig. 1) and Hordeum vulgare. In Tamus communis, while the side 

 walls exhibit the usual arrangement of isolated groups of threads, 

 the end walls are traversed by a single large group, as in sieve-tubes. 

 The structure of the endosperm cells of Lilium mar tag on (fig. 2) is 



Fig. 1. 



of some interest. The cells are pitted and each pit has its group of 

 " pit-threads." In any given group the threads are arranged in 

 bundles, recalling the similar arrangement of achromatin fibres, 

 which Strasburger and others have found to accompany nuclear 

 divisions in this plant. The mode of development of the threads 



