94 Trans. Acad. Set. of St. Louis. 



The term sclerid was proposed by Tschirch (451) for those 

 mechanical elements which are much shorter than bast cells, 

 as a rule not fusiform but blunt, with walls often greatly 

 thickened, stratified and lignified, with oval or rounded pits. 

 In the strongly thickened forms, pore-canals occur. In a later 

 work (265) he adopts the same classification and expands 

 somewhat on the Malpighian cells.* In the joint work of 

 Tschirch and Oesterle the same term is applied. Haberlandt 

 (85) uses the same term in a general way but calls the 

 Malpighian cells of leguminous seeds " palisade sclerenchy- 

 ma " and refers these to the same category as those found in 

 the seeds of Cannabis. 



It is obvious from what has been said that the term palisade 

 should not be used, as it is usually applied to the elongated, 

 thin-walled parenchyma of the leaf, where it has an important 

 function to perform in connection with photosynthesis , while the 

 function of the Malpighian cells is chiefly mechanical. I have, 

 therefore, adopted Tschirch' s general classification and for 

 this special case the term " Malpighian." Concisely stated, 

 these cells are longer than broad, with blunt or rounded ends 

 and one or more clear, lucid lines extending across the narrow 

 diameter, the so-called light lines. In the order Leguminosae 

 these cells are nearly universal. They vary in size just as the 

 seed does. They are strongly developed in Gymnocladus and 

 Glediischia, less so in Trifolium, some species of PJtaseolus 

 and MedicagOi nearly wanting in 8tylosanthes and Arachis, 

 and absent from Chapmannia. Under ** light line" I have 

 discussed these cells in various orders besides the Leguminosae. 



* Tscbirch's classification is as follows : — 

 A. Sclerids. 



1 Bracbysclerids. Nearly isodiametric, strocgly thickened. Cortex, 



Quercus and pimenta. 



2 Macrosclerids. Elongated with blunt ends. 



Palisade cells of leguminous seeds: — Trigonella, Physostigma. 

 Testa of Bicinus, Croton, and spicular cells in the seeds of species of 



Welwitschia. The sclerenchyma fibers of cocoanut fruit. The 



brittle inner layer of the nutmeg. 



3 Osteosclerids. Enlarged at both ends like the human femur. In leaf of 



tea. Support cells (I-shaped cells, T-shaped cells") occurring in the 

 inner layers of many seeds, as Abrus and Trigonella. 



4 Astrosclerids. Many branched sclerids, the branches mostly with a 



conical point. In leaves of Camelliaf Dammaray and bark of pine . 



