816 



STARCHES OF MAKANTACEjE. 



irregularities being chiefly the result either of protuberances or depressions in the surface of the grain. 

 The protuberances are more often located either near or at the proximal end. They may be present 

 at the corners of the distal margin of triangular grains and at the distal end of ellipsoidal or other 

 elongated types. These protuberances may vary from rounded, pointed, and nipple-like to rather 

 large cone-shaped, the latter type always being located at the proximal end. A depression at one 

 side of the hilum is often found in the mussel-shell-shaped grain, and a concave indentation resem- 

 bling a pressure facet is occasionally present at or near the distal end of such grains. The conspicuous 

 forms are ovoid, ellipsoidal, pyriform, triangular with curved base and rounded angles, nearly 

 round, mussel-shell-shaped, and ellipsoidal with a mesial elevation of one side. There are also im- 

 perfect quadrangular with rounded angles, club-shaped, lenticular, and finger-shaped grains. The 

 grains are somewhat flattened, and when viewed on edge 

 they are usually ovoid in shape, with the narrower end 

 towards the distal end. 



The hilum may be observed as a clear, round, or len- 

 ticular spot, generally eccentric, the range of eccentricity 

 being from four-ninths to one-fourth, usually one-third 

 to one-fourth. The variation is caused by the presence 

 of additional lamellte at the proximal end. Either a 

 small, rounded cavity or one or more fissures are often 

 observed at the hilum. In the broadened grains the fis- 

 sures frequently form a Y-shaped figure, while in the 

 elongated forms either one short, transverse cleft, one 

 crescent-shaped cleft, or two slightly curved, small fis- 

 sures so arranged as to resemble a soaring bird are often 

 found. In ellipsoidal grains with one side slightly ele- 

 vated mesially, the hilum is laterally located at this 

 elevated point. 



The lameUxe are demonstrable on most grains and 

 are fine, less fine near the hilum than towards the distal 

 end, at which margin in the shell-shaped grains there is 



often a band of very delicate or indistinct lamellae. They form complete, circular rings near the 

 hilum, but at other regions of the grain they closely follow the margin and are probably incom- 

 plete. On the larger grains 28 to 32 lamellae may be counted. Occasionally when the protuber- 

 ance on the grain is large, a depression is noted between the main body of the grain and this deposit, 

 which indicates that the lamellae of such a protuberance may be a secondary set of lamellae. 



The grains vary in size; the smaller are 3 by 2fi, the larger, 3G by 20/^ in length and breadth. The 

 common size is about 24 by IQ/x in length and breadth. 



Polariscopic Properties. The figure is quite eccentric to slightly eccentric, and occasionally 

 centric. Its lines are distinct, fine, and usually cross each other obliquely. They are generally 

 straight, but are sometimes bent, and rarely bisected. 



The degree of polarization is high, with slight variation in different grains, a few being very 

 high. Occasionally there are variations in the same aspect of a given grain. 



With selenite the quadrants are clearly defined and clean-cut, usually unequal in size, and some- 

 times irregular in shape. The colors are generally pure. 



Iodine Reactions. With 0.25 per cent Lugol's solution the grains color a fairly deep blue- 

 violet at once, which deepens gradually, some becoming much deeper than others; with 0.125 per 

 cent solution the grains color a rather light blue-violet which deepens in most grains rather rapidly. 

 After heating in water until the grains are gelatinized and then adding iodine, the grains become a 

 dull, quite deep blue, some with reddish tint, and the solution a rather deep indigo-blue. If the 

 gelatinized grains are boiled for 2 minutes and then treated with iodine, the solution colors a very 

 deep indigo-blue and the grain-residues a light blue, some with reddish tint, and the capsules a 

 reddish-violet. With an excess of iodine the capsules color an old-rose to a deep heliotrope. 



Staining Reactions. With gentian violet the grains begin to color slightly at once and in 30 

 minutes are fairly colored. 



With safranin the grains begin to color slightly at once and in 30 minutes are fairly deep in 

 tint, rather deeper than with gentian violet. 



Curve of Reaction-Intensities of Starch of 

 arundinacea. 



MINUTES 

 Maranta 



