402 STARCHES OF LEGUMINOSiE. 



Differeniiation of Certain Starches of the Genus Lathyrus. — Continued. 



Effects of Various Reagents. — Continued. 

 Reaction tinth Chromic Acid. — Continued. 



L. latifolius var. albus: Begins at once; complete in all 



in 3J<i minutes. 

 L. magdlanicus var. albus: Begins at once; complete in 



all in 4}^ minutes. 



Reaclion with Pyrogallic AcUi. 



L. odoratus var. shahzada: Begins in a few at once; com- 

 plete in all in 5 minutes. 



L. Bylvestris: Begins at once; complete in all in IJ^ 

 minutes. 



L. latifolius var. albus: Begins at once; complete in all 

 in 2 minutes. 



L. magellanicus var. albus: Begins at once; complete in 

 all in 4 minutes. 



Reaction with Ferric Chloride. 

 L. odorattts var. shahzada: Begins in all in 4 minutes; 

 complete in one-fifth in 1 hour. 



Effects of Various Reagents. — Continued. 

 Reaction vrilh Ferric Chloride. — Continued. 



L. sylvestris: Begins in all in 30 seconds; complete in nine- 

 tenths in 30 minutes and in practically all in an 

 hour. 



L. latifolius var. albus: Begins in all in a minute; com- 

 plete in nine-tenths in an hour. 



L. magellanicus var. alius: Begins in a few in 1 minute; 

 comjilete in two-fifths in 30 minutes and incomplete 

 in an hour. 



Reaclion with Purdy's Solution. 



L. odoratus var. shahzada: Begins in a few in 30 seconds, 

 in all in 4 minutes; complete in one-half in 30 

 minutes, but incomplete in an hour. 



L. sylvestris: Begins at once; complete in all in 30 minutes. 



L. latifolius var. albus: Begins at once; complete in prac- 

 tically all in 30 minutes. 



L. magellanicus var. albus: Begins in some in 30 seconds, 

 in all in 5 minutes. Complete in half in an hour. 



NOTES ON THE STARCHES OF LATHYRUS. 



It will be noticed from the photographs that the starches of the first three Lathyri are almost 

 identical in general appearances, and that such differences as are detectable are to be found in vari- 

 ations in the degree of regularity of the grains, the extent of fissuration, and the visibility of the 

 lamellae, all of which may be merely incidental and due to transient conditions, and therefore of no 

 real value in differentiation. But the starch of L. magellanicus var. albits stands by itself, the grains 

 being on the whole distinctly larger, more irregular, and more fissured. In the reactions more or less 

 marked differences are observed, the sum of which in the case of each starch is diagnostic. The range 

 of variation is particularly noticeable in the polarization, iodine, and temperature records, and in all 

 of the records of the chemical reactions. The wide range in the temperature reaction is very striking, 

 the lowest record being observed in L. sylvestris (58° C), aiid the highest in L. magellanicus var. albus 

 (69°), a difference of 11". In general, L. sylvestris and L. latifolius var. albus are closely in accord 

 in their reactions, while L. odoratus var. shahzada and L. 7nagellanicus are in correspondence. 



GENUS PISUM. 



The small genus Pisum is allied to Vida, Phaseolus, Lens, and Lathyrus, especially the latter, 

 and is composed of about a half a dozen species of climbing plants which are native chiefly to the 

 Mediterranean region and Asia. P. sativum Linn., the common garden pea, of which a considerable 

 number of agricultural forms are cultivated, is the best known of the genus. Apart from the members 

 of this genus, there are a large number of plants or seeds which are known as peas, some of which, 

 however, have not even a family relationship. Starches were prepared from five garden varieties 

 of P. sativum, the selection being based upon external characteristics of the seeds, including Eugenie 

 (a large, yellow or green wrinkled seed, the larger proportion being yellow and the remainder vari- 

 ous tints of green, mostly light) ; Thomas Laxton (a large yellow, wrinkled pea) ; Electric Extra Early 

 (a small, green, round, indent) ; Mammoth Grey Seeded (a large, brown, or greenish-brown, or gray, with 

 minute black specks, pitted, sugar pea); and Large White Marrowfat (a large yellow, smooth, round). 

 The Eugenie, Large White Marrowfat, and Mammoth Grey Seeded are late blooming varieties; 

 Thomas Laxton and Electric Extra Early are early blooming. Great importance was attached to 

 the properties expressed by the terms round and wrinkled, and green and yellow, in the experiments 

 by Mendel, which laid the foundation for the present-day Mendelism. (See Part I, page 72, for 

 starch in relation to Mendelism.) 



STARCH OF PISUM SATIVUM VAR. (EUGENIE, GREEN). (Plate 8, figs. 47 and 48. Chart 45.) 



The starch was prepared from the greenest of the separated green grains. 



Histological Characteristics. — In form the grains appear to be simple and chiefly as rosette and 

 linear aggregates. They may be divided into two groups; those appearing to be the original graias 

 and those appearing to be pieces of broken-down originals. The former are of round, ovoid, oval, or 

 linear types, but all are divided by deep, wide, often irregular fissures into from two to eight parts. 



