240 F. 0. BOWEE. 



him to conclude that chlorophyll bodies, starch-forming 

 corpuscles, and colouring bodies such as are found in the 

 cells of flowers and fruits, are closely related bodies; and 

 further^ that they all have a common origin. As in the 

 case of the nuclei of cells, they are the results of division of 

 colourless spheres, which coincide in their material characters 

 with the starch-forming corpuscles previously described by him. 

 These spheres may be found in all growing points ; in some few 

 cases chlorophyll may be found, even in the tissue of the growing 

 point. He states also that in the growing points themselves 

 these structures do not originate by differentiation from the 

 cell-plasma, but they are the products of the division of similar 

 starch-forming corpuscles or chlorophyll bodies, which may be 

 found in the embryo while still young (figs. 1 and 4). It is 

 probable that these structures are never formed free in 

 the protoplasm, but, like the nuclei of cells, are continued 

 by division from one generation to another. 



So great an advance on our former views of these bodies 

 and of their relations one to another made it necessary to 

 adopt a new terminology, and Schimper has proposed the 

 following, which appears to answer the requirements of the 

 situation. He applies to the whole series of these closely 

 related bodies the general term Plastids,^ and divides them 

 into three groups, which are named according to their most 

 prominent characteristics, viz. according to their colour, as 

 follows: — The starch-forming corpuscles are termed Leuko- 

 plastids, since they have no definite colour, but are a yel- 

 lowish white; the chlorophyll granules are called Chloro- 

 plastids; and to the colouring bodies of flowers and fruits 

 the name Chromoplastids is applied. Of these several 

 categories the Chloroplastids are always originally derived from 

 Leukoplastids, and the Chromoplastids from Leuko- or Chloro- 

 plastids. Thus the products of the Leukoplastids which are 

 found in Meristems have a different fate, according to the organs 



» It may be objected that this terra has already been applied by Haeckel 

 (' Generelle Morphologie/ Bd. i, p. 269) in another sense, but the term has 

 never obtained a hold in botany in the sense in which it was used by Haeckel. 



