284 BOTANICAL GAZETTE [april 



lignified walls ; the cells contain a considerable quantity of reducing 

 sugar. 



Tilia: Pericarp. — This is composed of two layers: (i) a surface 

 region of loose fibers with cellulose walls, and (2) a thicker region of 

 lignified fibers. Seed coat. — This consists of 3 regions: (i) cells 

 with suberized or cutinized walls; (2) one layer of paHsade cells 

 with (a) outer end walls of cellulose, (b) a lignified light zone, (c) a 

 pectinized region, and (d) a Hgnified region; and (3) 3 or 4 layers of 

 cells with walls which stain with ruthenium red and give the eerie 

 acid test. 



RuBUS: Endocarp. — This consists of 2 layers: (i) an outer 

 layer, variable in thickness, of lignified fibers longitudinally arranged 

 in cross-section of the fruit; (2) an inner region of 4 or 5 layers of 

 lignified fibers transversely arranged in cross-section of the fruit. 

 Testa. — This consists of 4 regions: (i) i layer of cushion-shaped 

 cells with lignified walls; (2) 4 layers of collapsed cells with cellulose 

 walls; (3) I layer of collapsed cells with thick pectinized walls; 

 and (4) I layer of cells with cellulose walls which appear as a 

 thickened outer wall of the endosperm. 



Microchemistry 



In table I are given the results of the microchemical tests made 

 upon the endosperm and embryo of each of the kinds of seeds used. 

 Owing to the lack of a sufficient number of germinating seeds of 

 Sa?nbucus several of the tests have not been completed. The 

 storage materials in all the seeds are very similar, starch, fats, and 

 protein being found in every case. In addition to these Sambucus 

 contains amylodextrin. Tilia contains much more fat and phytos- 

 terol than either Sambucus or Rubus. The phytosterol shows up 

 as a bright red layer around the fat globules when sections of the 

 seeds are placed in concentrated sulphuric acid. Oxidase is present 

 in the dry seeds in very small quantities, and in the germinating 

 seeds benzidine gives a positive test only after several hours. 

 Peroxidase, while present in dry Tilia seeds, is much more abundant 

 in the germinating seeds. Dry seeds of Sambucus and Rubus give 

 no peroxidase reaction. Catalase is found in both dry and ger- 

 minating seeds of all 3 species. 



