GENUS CALOCHORTUS. 



517 



The reaction with chromic add begins at once and is over in about 20 seconds. The process 

 api)ears to consist in a rapid swelling of the liiUnn, and a movement of the inner substance of the grain 

 to the distal end, where later it becomes gelatinous and swells in the form of a lobular, irregular 

 mass. As the grain swells the proximal end invaginates and then dissolves, and the solution of other 

 parts of the grain follows rapidly, the last part to dissolve being the lobulated distal end. 



The reaction with pyrogallic acid begins immediately and is over in 2 minutes. The hilum 

 becomes very prominent and then swells. The distal end becomes gelatinous and swells irregularly, 

 causing it to be much folded and lobulated. The pro.ximal inner portion of the grain passes into 

 a gelatinous mass. The more resistant starch at the margin forms a homogeneous band which at 

 first is quite broad. This band becomes thinner and transparent; the whole grain continues to swell, 

 and a large, thin-walled gelatinous mass is formed that is smooth and rounded at the proximal end 

 and very irregularly lobulated at the distal end. 



With ferric chloride the reaction begins in 30 seconds and is over in 4 minutes. The hilum 

 becomes prominent. The grains are invaded at the distal end by small fissures, at which point the 

 starch becomes gelatinous. This process proceeds from the distal end with great rapidity, causing 

 much sacculation, until the edge of the more opaque portion surrounding the hilum is reached. 

 Then the hilum swells suddenly upward, with enormous increase in size. The central, unswollen 

 part of the grain becomes divided by fissures, followed by sudden partition, each part gelatinizing 

 independently. There is thus formed a very large, clear, irregular mass that is much sacculated, 

 especially at the distal end; the proximal end may be fairly smooth and rounded. The gelatinized 

 grains are somewhat difficult to distinguish in the surrounding medium. 



With Purdy's solution the reaction begins immediately and is over in 30 seconds or less. Both 

 hilum and lamellae become very distinct. The hilum swells and the distal end of the grain becomes 

 gelatinized and swells out irregularly; the inner, ungelatinized part passes into a thin, gelatinous mass. 

 The starch at the margin forms a fairly broad, homogeneous band, which rapidly becomes thinner and 

 transparent as the grain continues to swell. The gelatinized grains are very large and smooth or some- 

 what folded and wrinkled at the proximal end, and very irregularly lobulated at the distal end. 



STARCH OF CALOCHORTUS HOWELLII. (Plate 29, figs. 173 and 174. Chart 125.) 



Histological Characteristics. In form the grains are simple, and with rare exceptions they are 

 isolated. They are without pressure facets. The surface of the grains is somewhat irregular, owing 

 to the uneven development of different parts of the 

 grain, and to secondary depositions. The most conspic- 

 uous form is the broad, short elliptical. There are also 

 ellipsoidal forms having a very broad fan-like distal end; 

 also ovoid, triangular, round, and polygonal with rounded 

 corners. The grains are somewhat flattened, and some 

 are narrower at one end than at the other. 



The hilum is generally very distinct. When not fis- 

 sured it appears usually as a large, round, or transverselj^ 

 elongated cavity that communicates with the interior of 

 the grain. It is eccentric about one-fifth of the longi- 

 tudinal diameter of the grain and located usually in the 

 smaller end. The grains often show two fissures or lines 

 which extend from the hilum, one on each side. When 

 the hilum is fissured the fissure is generally a short, 

 straight, longitudinal line, or there may be two lines 

 ruiming obliquely on each side. There are no double 

 or multiple hila. 



The lamella; are distinct, rather fine, continuous rings, 

 not so fine but more distinct near the distal end. They 



follow the outhne of the margin of the primary part of the grain and are somewhat irregular, owing 

 to unevenness in the surface. They seem to be arranged so that one or two larger lamellae alternate 

 with groups of finer lamellae. There aie about 16 to 18 on the larger grains. 



The grains varj' in size from 5 to 40^. The common size is 28^. The elHptical grains are usually 

 28 by 19/x, and the broader grains are 30 by 24/i in length and breadth. 



Curve of Reaction-Intensities of Starch of 

 Calochortus howellii. 



