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 

 Malpio-hian cells of leguminous seeds " palisade sclerenchy- 

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

 the seeds of Ca^mahis. 



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. 1 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 ju-^t as the 

 seed does. They are strongly developed in Gi/mnodadus and 

 Gleditschia, less so in Trifolium, some species of Pliaseolus 

 and MedicagOy nearly wanting in Stylosanthes and Arachis, 

 and absent from C liapmannia . Under " light line" I have 

 discussed these cells in various orders besides the Leguminosae. 



* Tschirch's classification is as follows: — 

 A. Sclerids. 



1 Brachysclerids. Nearly isodiametric, strongly thickened. Cortex, 



Quercus and pimenta, 



2 Macrosclerids. Elongated with blunt ends. 



Palisade cells of leguminous seeds: — Trigonella, Physostigma. 

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



Wehoitschia. The sclerenchyma fibers of cocoanut fruit. The 



brittle inner layer of the nutmeg. 



3 Odteosclerids. 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 Astrosclerlds. Many branched sclerids, the branches mostly with a 



conical point. In leaves of Camellia, Dammara, and bark of pine. 



