70 DIFFERENTIATION AND SPECIFICITY OF STARCHES. 



A. Monarch Starch-Grains. — Continued. 



tone rod-shaped starch-grains arise by starch-grains growing simultaneously 

 with the viscous chloroplast, and becoming unilaterally extended. The thinness 

 of the stretched sides of the chloroplast results in the formation of eccentric lamel- 

 lae. When the chromatojihore is first mature and a strong polytone growth of 

 the starch-grains prevails, the chromatophore is expanded so that the starch- 

 grain is somewhat broader at the base. 



(6) Monarch solitary, eccentric, conical. Lamella? arc the densest at one side and the 



most delicate at the diametrically opjjosite side. Grains are conical; circular in 

 transverse sections. Hilum located at the narrower, less dense end. (Nageli, 

 Type 6.) Examples: Starch-grains in the tuber of Solanuni tuberosum and 

 rhizomes of Adoxa. Starch-grains of Type 6 are found in chromatophores, which 

 show a tendency to gro^Hh equally in all directions. Pure forms usually only 

 occur when the monotone grain is half-grown. 



(7) Monarch solitary, eccentric, inverted-conical. Grains similar to those in Type 6, but 



with the hilum at the more dense end. (Nageli, Type 7.) Examples: Tuber 

 of Solanum tuberosum, rhizomes of Adoxa and Iris germanica, etc. By a flatten- 

 ing and then a sharpening to a point at the base of a grain of Type 6 with closed 

 lamella?, such type may develop into one of Type 7 with lamella? open at the base. 

 Grains of Type 7 are usually found in company with those of Types 5 and 6. 



(8) Monarch solitary, eccentric, flattened. Examjiles: Starch-grains in rhizomes of 



Zingiber officinale, Curmma zeodaria, Maranta, pseudo-tubers of Phaius grandi- 

 florus, etc. The starch-grains of Tj'pe 8 are formed in the same way as those of 

 Types 6 and 7, only they are flattened. 

 (6) Adel-phoxis starch-grains. 



I. Oligoadelphous starch-grains. If several starch-grains grow simultaneously in a chro- 



matophore, they behave just as spherocrystals do when growing in an inex- 

 haustil)le mother liquor. Starch-grains from Pellionia are an example. Only in 

 the very earliest stage are the two starch-grains spherical, ami, as is ajiparont, 

 the spherical shape is the more pronounced the larger the chlorojjlast when the 

 first grains start to form. If the chloroplast is still small when the starch-grains 

 begin to grow, so that the grains develop along with the chloroplast and exceed 

 it in growth, they are very soon prevented from increasing iia size on the inner 

 side, and both become flattened. The lamellae are heaviest within and below, 

 and in purely monotone grains they are always closed, since the crystallization 

 substance between the grains is furnished in the greatest quantity. Flattening 

 of the grains results, as is readily seen if one considers that when two spherical 

 grains grow side by side in a chromatophore, the chromatoi)hore layer being 

 thinnest where the two spheres come in closest contact with their surfaces. The 

 entire process of growth of the diadelphous starch-grains is similar to that of 

 monarch, solitary grains of Pellionia. 



II. Polyadelphous starch-grains. The polyadelphous starch-grains of a chromatophore, 



which are not easily distinguished from the diadelphous forms, are approximately 

 similar in form and size, though the proportion of the diameter of the smallest 

 to that of the largest is usually as 1 to 4. The greatest diameter of a chromato- 

 phore filled with starch-grains which was measured by Nageli is 106yu. Such a 

 chromatophore may, according to Nageli, contain between 10 and 30,000 grow- 

 ing starch-grains. The form of the polyadelphous grains is mostly polyangiilar 

 or rounded with centric structure. Some exceptions are found in the flattened 

 forms of Arenaria and ^4. graminifolia and Drymaria cordata described by Nageli. 

 The polyadelphous grains are fountl relatively seldom in rhizomes and roots, 

 although there are some exceptions, but occur most abundantly in the reserved 

 footl of seeds. The development of starch-granules in the chromatophore of the 

 endosperm of Oryza saliva served as a good example of the formation of polya- 

 delphous starch-grains. In every young seed of Oryza the nucleus lies in the 

 abundant cytoplasm in the center of the cell, and is surroundetl bj- small, scarcely 



