430 



STARCHES OF CUPUUFERiE. 



Differentiation of Certain Starches of the Genus Quercus. — Continued. 

 Effects of Various Reagents. — Continued. Ekfects op Various Reagents. — Continued. 



Reaclion wilk Pyrogallic Acid. — Continued. 



Q. prinus: Begins immediately; complete in 45 seconds. 

 Q. riAra: Begins immediately; complete in 30 seconds. 

 Q. texana: B^ins immediately; complete in 28 seconds. 



Reaetian with Ferric Chloride. 



Q. alba: Begins in many in a minute; complete in all but 

 rare resistant grains in 30 minutes, all in an hour. 



Q. muMenbergi: Begins in a few in 45 seconds; complete 

 in all but rai-e resistant grain in 45 minutes. 



Q. prinus: Begins in a few in a minute; complete in all but 

 rare resistant grains in 30 minutes, ajl in 1 hour. 



Q. rubra: Begins in a few in a minute; complete in all 

 but rare resistant grains in 15 minutes; complete 

 in these usually in 30 minutes. 



Q. texana: Begins in a few in 45 seconds; complete in 

 all but rare resistant grains in 15 minutes, com- 

 plete in these in usually 30 minutes. 



Reaction with Purdy's Solution. 



Q. alba: Begins immediately; complete in all but rare re- 

 sistant grains in 3 minutes, usually complete in 

 these in 5 minutes, rarely in 15 minutes. 



Q. nmehlenbergi: Begins in majority in a minute; com- 

 I)lete in nine-tenths in 30 mmutes, all but a few 

 scattered grains in an hour. 



Q. primis: Begins in a few immediately; complete in 30 

 minutes. 



Q. rubra: Begins in a few immediately; complete in the 

 central portion in a small percentage of grains in 

 30 minutes, not so complete as in Q. alba. Incom- 

 plete in an hour. 



Q. texana: Begins in a few immediately; complete in the 

 central portion of a larger percentage of grains in 

 30 minutes than in Q. rubra; some resistant starch 

 remaining in 60 minutes; not so complete as in Q. 

 alba. 



NOTES ON THE STARCHES OF QUERCUS. 



Some minor differences are noted in the histological characteristics of the five oak starches. 

 In the case of the reactions, except of those with gentian violet, the differences in each starch are 

 diagnostic in relation to the others. The starches which correspond most closely in their reactions 

 are those of Q. rubra and Q. texana, which are closely related species. Q. rubra has the lower degree 

 of polarization ; lower sensitivity to iodine, chromic acid, and Purdy's solution; and a lower tem- 

 perature of gelatinization (1.25°). In the gentian violet, chloral hydrate-iodine, pyrogallic acid, 

 and ferric chloride reactions they are practically identical. 



GENUS CASTANEA. 



Several species of Castanea are largely cultivated in certain parts of Europe, Asia, Northern 

 Africa, and America, and from these and from the trees or shrubs growing wild, large quantities 

 of edible fruit or nuts are gathered. In this country the cultural forms are referred to the common 

 American sweet chestnut {Castanea americana) ; the European chestnut (Castanea saliva), which is 

 also known as the Italian, Spanish, and French chestnut, the fruit of which is much larger, but 

 less sweet and of inferior flavor; the Japanese chestnut (Castanea crenata), which has a large fruit, 

 but of rather poor quality; and the chinkapin (Castanea pumila; C. alnifolia), the fruit of which 

 is small. There are many cultural varieties of Castanea, and much has been done in the cultivation 

 of selected forms, especially by grafting on species of either Castanea or Quercus — in the case of the 

 latter, especially Q. prinus or the chestnut oak. Starches from four sources were studied : C. ameri- 

 cana Raf. (C. dentata Bokh.), C. sativa var. numbo, C. saliva var., and C. pumila Mill. 



STARCH OF CASTANEA AMERICANA. (Plate 12, figs. 69 and 70. Chart 69.) 



Histological Characteristics. — Inform the grains are usually simple, and are isolated, except some 

 which occur in clumps and in small aggregates. There are a few compound grains of usually two or 

 three components. Some of the isolated grains have well-marked pressure facets. The surface of the 

 grains is frequently irregular, owing chiefly to wart-like protuberances at one or more points. These 

 growths are generally located at either end of an ellipsoidal grain and appear less dense than the 

 main portion of the grain. The conspicuous forms are ovoid, somewhat bean-shaped, ellipsoidal, club- 

 shaped with pointed end, and pyriform. There are also triangular with rounded angles, lenticular, 

 dome-shaped, napiform, pyriform with curved distal end, and irregular grains of indefinite shape. 



The hilum is not usually demonstrable. Occasionally it may be observed as a clear, round spot, 

 which may be centric, but is usually eccentric about two-fifths to about one-third of the longitudinal 

 axis. Rarely a .small irregular cavitj' is found at the hilum. A single longitudinal cleft, with or with- 

 out radiating fi.ssures, sometimes proceeds from the hihnn. Either a short transverse or diagonal cleft is 

 occasionally found, which may pass through or be located just beneath the distal margin of the hilum. 



The lamellcE are rarely demonstrable, but when observed are rather coarse, complete rings 

 which follow the outline of the grain. The lamellffi of the main body of the grain do not pass into 

 the wart-like excrescences above referred to, and in which no lamellai are demonstrable. 



