214 SUMMAKY OF CUEKENT EESEAECHES EELATING TO 



Formation of Resin in Plants.* — Herr A. Tschirch describes in 

 detail the mode of formation of the oil-cells in Cinnamomum Cassia. 

 They are developed from small cells filled with protoplasm, by the 

 gradual suberisation of the cell-walls, accompanied by the formation of 

 a layer of mucilage. Ultimately the inner strata of the mucilage-layer 

 become absorbed, and the protoplasm fuses with the remainder of the 

 mucilage ; and the resinogenous layer results from their \mion. Small 

 drops of oil are formed in it, which gradually pass into the cavity ; and 

 the resinogenous layer is finally almost entirely resorbed. Similar 

 phenomena are presented by other resin-plants. 



Excretion of Resin by the Leaves of Conifers.-f— From the obser- 

 vation chiefly of species of Pinus, Picea, Abies, and Juniperus, Herr E. 

 Schwabach draws the following general conclusions. 



The resin is formed in the epithelial cells of the resin-passages of 

 young leaves, and from them is excreted into the canal. This excretion 

 begins as soon as the canal-cells are differentiated, so that the canal 

 becomes at once filled with resin. In Abies, Pinus, and Juniperus, the 

 walls of the epithelial cells do not thicken, and continue to pour out 

 resin into the canal. In Picea the walls of the epithelial cells begin to 

 thicken in the first year, so that the cell-cavity often disappears almost 

 entirely. The thickened membranes subsequently become absorbed ; 

 in which process, in Picea, resin is sometimes formed as a secondary 

 product. 



Indican and Pseudindican. % — I n tne case of several indigo-pro- 

 ducing plants — Indigofera, Isatis tincioria, Phajus grandifolius, Herr H. 

 Molisch has determined that the indican is produced chiefly, though not 

 entirely, within the chlorophyll-grains. This affords the first example 

 of the presence of a nitrogenous glucoside within the grains of chloro- 



In the cystolith-cells oi a few species belonging to the Acanthacete, 

 but not in others, the same author § finds a chromogen giving the same 

 reactions as indican, but very unstable. For all such chromogens which, 

 under similar conditions, produce blue or blue-green pigments, he pro- 

 poses the term pseudindican. 



Atropine in Datura-seeds, jj — Dr. J. Thomann has made a series of 

 observations for the purpose of determining whether the atropine in the 

 seeds of Datura stramonium is a waste product or a reserve food-material. 

 He finds sufficient evidence that, during the germination of the seeds, 

 the greater part of the alkaloid is absorbed even when the culture is 

 entirely free from bacteria or mould-fungi. 



(3) Structure of Tissues. 



Crystal-Cells.^" — Prof. W. Rothert and Herr W. Zalenski apply this 

 term to a peculiar kind of cell found only in Monocotyledons, and 

 apparently confined to the Iridere, Ainaryllideae, and some families of 

 Liliacea3. These cells differ in several respects from ordinary raphicl- 



* Festschr. f. Schwendener, 1899, pp. 464-70. 

 t Ber. Deutsch. Bot. Gesell., xvii. (1899) pp. 291-302 (1 pi.). 

 % Tom. cit., pp. 228-33 (1 pi.). Cf. this Journal, 1899, p. 181. 

 § S.B. k. Akad. Wias. Wien, cviii. (1899) 12 pp. and 1 pi. 

 || Bot. Oentralbl., lxxx. (1899) pp. 461-5. 

 1 Tom. cit., pp. 1-11, 33-50, 97-106, 145-56, 193-201, 211-51 (1 pi.). 



