CHIEF FORMS AND CLASSIFICATIONS OF STARCH-GRAINS. 67 



C. Grains Compound. The component part-grains not enveloped by a common substance. 



I. Composed of fused part-grains. 



Type 12. Composed of fused part-grains. The part-grains are not separated by fissures, 

 and even different grains may be fused with one another. 



II. Composed of separated part-grains. The part-grains separated by fissm-es. 



Type 13. Grains in 1 or 2 roujs. From 3 to 11 components arranged in 1 or 2 rows. 



Type 14- Equally divided grains of few components. From 2 to 10 or more almost equal-size 

 part-grains which when separated have 1 curved surface and 1 or more pressure facets. 



Type 15. Unequally divided grains of few components. From 2 to 10 or more unequal 

 sized firmly united part-grains, which when separated have 1 curved surface and sev- 

 eral flattened pressure facets. 



Txjpe 16. Multiple grains. From 20 to many thousand firmly united part-grains which 

 when separated are covered with pressm-e facets. 



Type 17. Hollow spherical grains. The part-grains are arranged in a spherical layer, as if 

 a globular shell had been divided radially. 

 For further details of the characteristics of the various types see Chapter V, page 197. 



Meyer's Classification of Starch-Grains. 



Mej-er, in his memoir Die Sttirkekorner {loc. cit.), criticizes Nageli's conceptions of the 

 "pseudo-compound" and "true-compound" starch-grains (Chapter V), and holds that we 

 must dismiss the idea of a "true-compound" grain in the sense held by Nageli because there 

 are no starch-grains that have been formed by the separation of an originally single grain. 

 The expression "pseudo-compound starch-grains" may also be rejected because it is now un- 

 suitable, since if there are no tnie-compound grains there can be no false ones; furthermore, 

 the grains under consideration are not individual starch-grains, but only simple starch-grains 

 held together by a chromatophore substance. The "semi-compound" grains which according 

 to NiigeU arise tlirough the division of the nuclei and the formation of systems of lamellae with- 

 out any lines of separation between the cells is also incorrect because such starch-grains arise 

 from several simple starch-grains being inclosed within a common starch-layer. Instead of 

 the old name of compound grains, to avoid confusion, it is better to substitute the expression 

 "complex" starch-grains; but Nageli's conception and term of "simple grain" may be retained. 



Meyer proposes some substitutes and some new terms in place of Nageli's, as follows : 



(a) Simple or monarch starch-grains. Grains which have but one hilum. 



lb) Complex starch-grains. Grains that are formed from several starch-grains which are so 

 crowded in one chromatophore that they become enveloped within common starchy 

 layers, and thus boimd into a single individual. Complex starch-grains may be 

 diarch to polyarch. 

 The approximately monotone starch-grains possess simple symmetrical forms; frequently 

 they are spherical bodies, the shape depending upon the influence which the fluid 

 chromatophore exerted upon the form and lamellae of growing starch-grains. Grains 

 of a relative monotone type are found chiefly in the nutritive tissues of seeds, in which 

 during the active growth of their cells and chromatophores an energetic and periodic 

 solution of the starch-grains takes place, by means of which the central mass of the 

 grain becomes relatively less dense, which in turn is followed by a uniform growth of 

 the starch which ceases when the seed matures. Similar processes take place in many 

 cotyledons which contain reserve material; also in numerous typical, colorless stor- 

 age roots and bulbs which are filled with starch during their growth, and contain, if 

 they vegetate normally, relative monotone starch-grains. Such organs during their 

 development, and especially at the period when the reserve material is admitted, 

 depend chiefly upon their neighboring structures for nourishment, and only in extreme 

 cases of need can they draw upon the stored starch-grains. Examples of monotone 

 starch-grains are found in the fleshy scale leaves of Adoxa, in the rhizome of Iris 

 gerynanica, and in the mature tubers of Solanwn tvberosuvi. In the latter monotone 

 starch-grains may develop within the parenchyma cells in 14 days. 



