STARCH-SUBSTANCE, AND THE STRUCTURE, ETC., OF THE STARCH-GRAIN. 43 



layer separates, and a part of it is in contact with and completely surrounds every one of 

 these bodies. This plasmic layer brings about the transformation of the body into starch 

 in such a manner that the albumin molecule is split by the action of the plasma. After 

 the solution of the entire body, and after the newly formed starch-grain has broken through 

 the plasmic layer, a part of this plasmic layer remains attached to the grain in the form of 

 a hood, which usually has attachment to the rest of plasm. (5) Such grains always show 

 eccentric lamellation which appears after the grains have broken tlirough the plasmic 

 layer. (6) No growth occurs after the disappearance of the plasmic hoods. (7) The plas- 

 mic layer or plasmic hoods might with reason be called starch-builders. 



The starch-building processes of non-chlorophyllous structures were also studied by 

 Konigsberger (Botanische Centralblatt, 1892, xliv, 47). This author gives the results 

 of his investigations of starch-building in Angiosperms. He does not agree with Schimper 

 that in many plants the starch-grain originates only in the peripheral parts of the chloro- 

 phyl-grains and soon breaks through the chloroplast, and on account of unilateral accre- 

 tion becomes eccentric. He observed starch-grains in the parenchyma cells of Pelargonium 

 which were eccentric although entirely inclosed by the chlorophyl. 



The following is a very brief summary of Konigsberger's results: (1) The formation 

 of reserve starch in Angiosperms takes place through the agency of the leucoplasts and 

 also by the direct activity of the protoplasm itself. The first process, which is observed 

 in many Monocotyledones and in only a few Dicotyledones, must be viewed as the earlier, 

 from which the second has been developed and predominates in many Dicotyledones. 

 (2) In the Dicotyledones the leucoplasts, having performed their function, have in many 

 plants entirely disappeared. (3) The beginning of the starch-grain is probably in the form 

 of a deposition of amylodextrin. (4) The capacity to polymerize carbohydrates of less 

 molecular weight into those of greater molecular weight, which latter are in the definite 

 form of reserve material, was originally peculiar to the leucoplasts, but in many of the 

 higher plants was later transferred to the protoplasm. (5) The starch-grains probably 

 originate from amylodextrin, and when the starch is rendered into a soluble form for pur- 

 poses of transportation it is reverted into amylodextrin. 



The form and method of formation of starch-grains were studied coincidently by 

 Dodel (Flora oder Allegemeine Botanische Zeitung, 1892, lxxv, 266) and Binz {ibidum, 

 1892, Lxxvi, 34). Both made their studies mostly with the starch from Pellionia daveauana. 

 Dodel makes rather general statements, while Binz goes somewhat into details. 



Dodel writes that after careful study he reached the conclusion that this plant fur- 

 nishes the most suitable material for the study of both the morphology of starch-grains 

 and of the starch-builders; that both grains and builders of Pellionia are well adapted to 

 answer the question as to whether or not the grains grow by intussusception or apposition ; 

 and that he is convinced that the growth is exclusively by apposition. He records that 

 a section of the stem at a young internode shows in the parenchyma region many starch- 

 grains of various sizes and forms, most of which have chloroplasts attached to them. In 

 the region of the fibrovascular bundles, and in the pith, the starch-grains have attained 

 most perfect and uniform development, while towards the periphery of the section the 

 grains and the chloroplasts decrease in size. The form of the grains was found to vary 

 considerably. All of the grains are stated to originate as small spheres which are found 

 in the middle or toward the periphery of the spherical or ovoid chloroplast. As soon as 

 the grains ha\'e attained sufficient size to protrude through the green starch-builders, the 

 spherical form is changed, and the grains begin to grow unilaterally, that is, the main point 

 of growth is where they are in contact with the chloroplasts, while the part of the grain 

 that is not in contact with the chloroplast not only grows slowly but finally ceases to grow. 

 The grains, at first spherical, soon become oval, wedge-shaped, reniform, cylindrical, or 

 irregular in shape. All of this diversity of form, he states, is due to growth by apposition. 



