ORIGIN OF CHLOROPHYLL GRANULES. 



287 



following view' appears to bj most in consonance with recent 

 investigations. Imbedded in the protoplasm at ever}- growing 

 point there are pecnliar 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 eai'l}' 

 period. As the cells which develop from the growing point 

 assume the different characters which lit 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 maj- likewise assume 

 special characters. Those which are destined' for the store- 

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

 tissue, chloroplastids or ciilorophyll granules ; and those in col- 

 ored flowers and fruits, chroraoplastids. 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 yet partly- h^-potheti- 

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

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



1 Meyei- (DaaCliliiropliyllkorn, 1883, and Botaiiisclies Central blatt, 1882) has 

 readied substantially the same results as those obtained by Schimjier, which in 

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

 Meyer employs, however, the somewhat differen t 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, 1R84). 



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 permeated 

 by cohn-ing-niatter. In most green algae 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/ 



