CELLULAR TISSUES. 



231 



lated ducts seen in fig. 137. In a section from the 

 India-rubber-tree, fig. 134, No. 2, a network of these lac- 

 tiferous tubes will be found filled with a brownish or 



Fig. 136. 



1, A portion of the leaf of Sphagnum, showing ducts, vascular tissue, and spiral 

 fibre in the interior of its cells. 2, Porous cells, from the testa of Gourd- 

 seed, communicating with each other, and resembling ducts. 



granular matter; that in fig. 135 is an enlarged view of 

 this tissue from the wood of an exogen, taken near the 

 root. 



_ 





Fig. 137. 

 1, Reticulated ducts. 2, A vertical section of Fern-root. 



In many plants external to the cuticle, there exists a 

 very delicate transparent pellicle, without any decided 

 traces of organisation, though occasionally somewhat gra- 

 nular in appearance, and marked by lines that seem to 

 be impressions of the junction of the cells in contact with 

 each other. In nearly all plants, the cuticle is perforated 



