with special Reference to the Mode of Connexion of Cells. 109 



that in all these tissues the threads perforating the pit-closing mem- 

 brane can be readily seen, and even counted. 



A point of interest was observed in the epidermal cells of T amus 

 communis and Lilium martagon (fig. 6), viz., that the external or free 

 walls are penetrated by a system of threads which radiate from the 

 cell lumen and extend to the cuticle, so that the latter is the only 

 structure intercalated between the protoplasm and the environment. 

 The important bearings of this observation are obvious. 



Fig. 6. 



The following is a list of the tissues which have up to the present 

 been investigated, together with the date of observation. In each 

 case connecting threads were observed. 



In 1894. The young and developing endosperm of Tamils communis 

 and the young endosperm of Asperula odorata.. 



In 1895. The cotyledons of Tropceolum majus. The endosperm of 

 Lilium martagon and Fritillaria imperialis. The root of Ranunculus 

 asiaticus. The leaf stalks of Tamus communis, Viscum album, and 

 Marattia elegans. 



In 1897. The leaf stalks of Aucuba japonica, Prunus laurocerasus, 

 Nerium oleander, Lilium martagon, Lilium candidum, Salisburia 

 adiantifolia, and Asplenium rutcefolium (fig. 7). The flower stalk of 



Fig. 7. 



