62 SUMMARY OF CURRENT RESEARCHES RELATING TO 



imbedded in colloidal substances. They are also soluble in water 

 (hesperidin, inulin, and other carbohydrates), or insoluble (starch and 

 the fundamental substances entering into the composition of the 

 cell-wall). 



In the cell-wall the crystalloids occur in very close radial and 

 tangential rows, and constitute by far the greater proportion of the wall. 

 In the starch-grain, on the other hand, there is apparently a greater pre- 

 ponderance of colloidal matter which takes up certain stains. The 

 structure, as well as the mode of formation of spherites and sphere- 

 crystals, appears to be the same. 



The author enters into further particulars with respect to certain of 

 these substances of both kinds, and compares them with those produced 

 artificially. 



Evolution of Chlorophyll and Starch in the Stem.* — J. d'Arbau- 

 mont has a very elaborate treatise on this subject, arranged under the 

 following heads : — Period of Formation ; Summer and Autumn ; Winter 

 Period ; Renovation in the Spring. The observations were made on a 

 large number of trees and shrubs belonging to many different natural 

 orders. 



In the course of his observations the author distinguishes between 

 two kinds of cell in which starch and chlorophyll are found : — cyanocysts, 

 which contain substances stainable by aqueous solutions of methylen- 

 blue and anilin-violet-blue ; and achroocysts, the contents of which do 

 not stain by these reagents. The chlorophyllous plastids, or chlorites, 

 are also classified under two categories: — gymnochlorites, or chlorites 

 contained in cyanocysts, which usually become detached at an early 

 period from the protoplasmic layer in which they were formed ; and 

 endochlorites, those contained in achroocysts, which remain for an in- 

 definite period enclosed within that layer. 



The special points investigated are as follows (for details the original 

 memoir must be consulted) : — The formation of amylo-chlorophyll in 

 the growing cone and the first internodes of the growing stem ; the 

 reciprocal relations of chlorophyll and starch in the course of the 

 summer and autumn, in other words, during the period when the stem 

 ceases to increase in length and establishes for each period a maximum 

 annual increase in diameter; the condition of starch and chlorophyll, 

 and of the medium in which they are imbedded during the winter ; the 

 phenomena of regeneration of which they are the seat on the return of 

 spring. In the adult stem are found the two kinds of amylo-chloro- 

 phyllous plastids mentioned above, distinguished both by their morpho- 

 logical characters and by their behaviour towards reagents. 



Structure of Starch.j — According to W. Syniewski, the composition 

 of starch itself is perfectly uniform, with the empirical formula C 6 H 10 O 5 ; 

 the more resistant constituent — starch cellulose, a-amylose — being a 

 reversion-product subsequently formed from the starch which has 

 become dissolved. The substances formed by the action of boiling 

 water or of KOH on starch-grains, are the product of the hydrolytic 



* Ann. Sci. Nat. (Bot.), xiii. (1901) pp. 319-423; xiv. (1901) pp. 125-212. 

 t Akad. Wiss. Krakau. naturw. CI., xxxix. (1899) (Polish). See Bot. Centralbl., 

 lxxxvii. (1901) p. 408. 



