ORIGIN OF CHLOROPHYLL GRANULES. 



287 



following view l appears to be most in consonance with recent 

 investigations. Imbedded in the protoplasm at every growing 

 point there are peculiar bodies (plastids) which have substan- 

 tially the same characters and structure as the protoplasm, and 

 are more or less clearly differentiated from it even at an eariy 

 period. As the cells which develop from the growing point 

 assume the different characters which fit them for special ser- 

 vice, for example, those in certain tubers and roots for store- 

 houses, those in leaves for assimilation, and those in some 

 flowers and fruits for color, their plastids may likewise assume 

 special characters. Those which are destined for the store- 

 houses become leucoplastids, or starch-formers ; those in green 

 tissue, chloroplastids or chloroph}-!! granules ; and those in col- 

 ored flowers and fruits, chromoplastids. As might be expected 

 from their common origin, the plastids which under one set of 

 conditions might become leucoplastids, may, under another set, 

 become chloroplastids, etc. 



767. The recognition of this view regarding the origin of 

 chlorophyll grains, etc., although it is as } r et parti}' hypotheti- 

 cal, will enable the student to explain some of the extraordi- 

 nary intermediate forms met with ; for instance, those where the 



1 Meyer (Das Chlorophyllkorn, 1883, and Botanisclies Centralblatt, 1882) has 

 reached substantially the same results as those obtained by Schimper, which in 

 the account above given have been presented with Schimper's nomenclature. 

 Meyer employs, however, the somewhat different terminology given below. 



For a fuller account of the views of Meyer and Schimper, the student must 

 consult the original memoirs in Botanische Zeitung, 1883, or an excellent 

 abstract by Bower (Quarterly Journal of Microscopical Science, 1884). 



Schmitz (Die Chromatophoren der Algen, 1882) has described at great 

 length certain structures analogous to chlorophyll, occurring in some of the 

 lower plants. These granular bodies, called chromatophores, possess consider- 

 able diversity of form, but all agree in consisting of a matrix or basis penneated 

 by coloring-matter. In most green algse there are also found one or more 

 minute, rounded, granular, colorless bodies embedded in the chromatophore, 

 known as pyrenoids. These are frequently associated with granules of starch. 

 Chromatophores are believed by Schmitz to increase only by the process of 

 division , but the pyrenoids either by division or by fresh formation. 



