378 On Sclerenchyniatous Cells. [Sess. 



X.— OiV^ SCLEBENCHYMATOUS CELLS. 



By Mr WILLIAM COATS. 



{Read March 26, 1890.) 



While examining the epidermis of the leaves of the Kaurie 

 pine (Bavimara australis), after Mr Hugh Fraser's interesting 

 observations on that tree, I noticed that certain scleren- 

 chymatous cells, which had become isolated through macer- 

 ation, existed in considerable numbers in the laminse of the 

 leaves ; and the hope that some of the members interested in 

 the intimate structure of plants might care to see these and 

 one or two allied forms under the microscope, is my reason 

 for now bringing this subject under the notice of the Society. 



On the night of our last meeting, I placed some leaves of 

 the Kaurie pine in a strong solution of caustic potash, in 

 which they remained for three and a half days ; and as they 

 were then showing signs of being sufficiently macerated, I 

 boiled them in the solution for fully a quarter of an hour, 

 the result being that the epidermis was loosened from the 

 underlying tissue, and the cells in question, on splitting up 

 the leaves and shaking them well in a tube, were detached as 

 they are now seen, apparently unaltered, except that they 

 are stained with aniline green. The epidermis of the leaf 

 showed what, from its hard and horny character, would be 

 expected — viz., that the stomata were in hundreds on the 

 under surface, arranged mostly in parallel rows, while on the 

 upper surface there was only one to be seen here and there. 



Sachs gives the name " idioblasts " to those individual cells 

 occurring in a tissue which, otherwise homogeneous, become 

 developed in a manner strikingly different from their neigh- 

 bours. These " idioblasts " he divides into " simple glands " 

 when they contain resin, oil, or gum ; into " lithocysts " when 

 they contain crystals or raphides ; and into " scleroblasts " 

 when the cavity of the cell becomes reduced to a narrow 

 canal or a small central hollow. When these scleroblasts 

 are associated in groups or layers, they form the tissue known 

 as " sclerenchyma." Scleroblasts are especially characterised 



