ON SOME PROTEIN CRYSTALLOIDS 



AND THEIR PROBABLE RELATION TO THE 



NUTRITION of the POLLEN-TUBE 



By the use of spécial fixing and staining methods, Zimmermann(i) has, 

 during the last few years, greatly extended our knowledge of Protein 

 Ciy T stalloids; and Stock (2), using the same methods, has rccently investi- 

 gated their relation to the metabolism of the plant. Apart altogether from 

 those found in aleurone grains, Protein Crystalloids may be classified 

 according to their position in the cell as, 



1. Nuclear Crystalloids. 



2. Cytoplasmic Crystalloids. 



3. Cell-sap Crystalloids. 



4. Ch'romatophoric Crystalloids. 



Nuclear Crystalloids. Zimmermann has found that, in the nuclei of 

 Pteridophyta and Angiosperms, Protein Crystalloids are of much more 

 fréquent occurrence than was formerly supposed. He has found them in a 

 very large number of Feras, and in 47 species of Phanerogams belonging to 

 ten différent families. 



Cytoplasmic Crystalloids occurring in the body ofthe cell hâve been 

 demonstrated only in a very limited number of instances. Much difficulty 

 has been experienced by observers in determining whether such crystalloids 

 really occur in the cytoplasm, or in the cell-sap, because ofthe thickness of 



(1) Zimmermann : Beitràge ^ur Morphologie und Physiologie der Pflanjen^elle \ Heft i, p 54 and 

 Heft 2, p. 112. 



(2) Stock : Ein Beitrcig jur Kenntniss der ProteinkrysialU ; Cohn's Beitràge zur Biologie der 

 Pflanzen, Bd. 6, 1892. 



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