112 Travis. Acad. Sci. of St. Louis. 



Vicieae. It is much less marked in such genera as Gledit- 

 schia and Phaseolus. In Medicago and Trifolium these 

 markings are conspicuous. 



The cell-walls give the characteristic reaction for cellulose 

 with chlor-iodide of zinc or with sulphuric acid and iodine. 

 In Mucuna, Gleditschia, and Cassia, lignification does not 

 occur as a rule. Slight lignification occurs in Bajytisia leu- 

 cojjliaea and is recorded for Baptisia australis by Mattirolo 

 and Buscalioni (174, x)l' 1- f- 5-19). The cell contains some 

 protein matters, and in some genera tannin and coloring 

 matter. Some species, notably Phaseolus vulgaris and P. 

 muUiJiorus, contain crystals of oxalate of lime. In the closely 

 related P. lunatus these crystals have not been found, nor in 

 any of the North American species studied. — Table C. 



Nutrient Layer. 



Tschirch (265, 1 : 301) applied the term " Nahrschicht " 

 to the layer following the osteosclerids, to designate its func- 

 tion in the immature seed. In the growing seed the cells of 

 this layer contain not only water but chlorophyll and transi- 

 tory starch, as I have shown for Strophostyles paucijlorus. 

 This starch serves to nourish the growing seed. Holfert 

 (116, 6), who has studied its character in several species, 

 observes that in Lupinus it consists of thirty rows of cells. 

 The nutrient layer is by no means confined to this order, as 

 the studies of Holfert as well as those of Schlotterbeck ( 439 ) 

 show. As the seed approaches maturity the cells collapse, 

 the cell-cavity appearing as a mere line. In Lupinus luteus 

 the layer is reduced one-half, and as much in Strophostyles. 

 This layer undoubtedly is also a conductor of elaborated and 

 unelaborated food products. The vascular elements begin 

 at the micropylar end of the seed and extend along the 

 raphe. These cells may also give some mechanical support. 

 In Mucuna urens the cells attain considerable development, 

 contain air, and are not compressed. Here they serve to 

 buoy the seed up in water, and thus afford an important means 

 for dissemination. The walls consist of cellulose, as micro- 

 chemical tests show. 



