GENERA ROMULEA AND CYPELLA. 751 



here stains a deep indigo and swells slightly. From these points tlio jjrocess spreads slowly inward 

 over the rest of the grain, accompanied by very slight swelling. The gelatinized grains are not very 

 large and retain much of their original form. 



Reaction with chromic acid begins in some grains in 15 to 30 seconds and is over in 33^ minutes. 

 The less resistant starch melts down into a semifluid mass occupying the center of the grain and 

 the more resistant starch forms a striated marginal band, which is broad at first but grows thin and 

 transparent, especiallj^ at the corners of the facets. Usually the resulting thin capsule is dissolved 

 at these points and the semiliquid central mass flows out and is fully dissolved, and the rest of the 

 capsule is also dissolved slowly. 



The reaction with pyrogallic acid is general in 15 minutes, and about half of the grains are fully 

 gelatinized and the rest are partially gelatinized in 40 minutes. The hilum and lamellce grow more 

 prominent and the grain becomes covered by fine striaj radiating in all directions from the hilum. 

 The less resistant starch melts down into a gelatinous mass occupying the central portion of the 

 grain and causing the grain to swell. The more resistant starch forms a fairly broad, dense, striated, 

 marginal band, which becomes gradually thin and transparent in the fullj' gelatinized grains; these 

 grains are fairly large and retain some of their original form, and the capsules are sometimes slightly 

 wrinkled and folded. 



With/e7Ttc chloride a very few grains begin to react in 2 minutes and one-third are affected; a few 

 are completely gelatinized in 13 minutes, three-fifths are completely gelatinized in 27 minutes, and 

 practically all in an hour. The reaction begins at the comers and edges of the facets. The starch 

 at these points becomes gelatinous and swells out irregularly, distending the capsule. From these 

 points the reaction spreads until all the starch at the base is involved, and then it spreads inward 

 over the rest of the grain. In some cases the less resistant material collects in the central part of 

 the grain in a gelatinous mass, causing the grain to swell and the more resistant starch forms a 

 dense marginal band which becomes gradually thin and transparent. The gelatinized grains are 

 large and retain some of their original form. The capsules are often wrinkled and folded. 



The reaction with Purdy's solution begins in a few grains in 30 seconds, and in an horn* a scattered 

 few show complete gelatinization and the rest show various stages of partial gelatinization. The 

 reaction presents the same appearance as that to pyrogallic acid. 



GENUS CYPELLA. 



This genus includes 8 species of bulbous plants, natives of Southern Brazil, Uruguay, and 

 Argentina. C. herberti is the only species in common cultivation in this country and from it was 

 obtained a specimen of starch representative of the genus. 



STARCH OF CYPELLA HERBERTI. (Plate 75, figs. 449 and 450. Chaxt 293.) 



Histological Characteristics. In form there are both simple and compound grains, a few clumps 

 but no aggregates; no pressure facets. The surface of the grains is rounded and tends to be some- 

 what irregular in outline. The conspicuous forms are the reniform to rounded reniform, with a 

 slight protrusion from the straightened edge, which is the pro.ximal end; also lenticular, elliptical 

 to almost round, and rounded triangular. The grains are somewhat flattened, the reniform grains 

 being about half as thick as long. 



The hiluni is always fissured, generally very deeply. It is very eccentric, and commonly in or 

 near the median line. It is sometimes double or multiple; and there may be two or more hila in the 

 compound grains. The fissures are usually very wide and deep and take the form of a very ragged 

 cross placed longitudinally or diagonally, and may include all the hila. In other cases there is an 

 irregularly stellate fissure, or when there are two or more hila there may be a corresponding num- 

 ber of irregularly stellate fissures. 



The lamella; are generally not very distinct; when seen, they appear as coarse, regular, con- 

 tinuous lines. They tend to follow the outline of the margin, but otherwise do not appear to have 

 irregularities. Near the hilum they are somewhat obscured by the deep fissures. There are probably 

 about 6 to 8 on a medium-sized grain. 



The grains vary in size from 4 to 48/i. The common size is 30/x. 



Polariscopic Properties. The figure is eccentric, fairly distinct, but not clear-cut, owing to the 

 broad diffused lines. One of its lines may be bisected, and rarely the lines may be bent. 



