CHAPTER XV 



sfüfiÏES ON STARCH, AND PROBLEMS OF COLLOID 



CHEMISTRY 



A short treatise of Beijerinck in 1912 on the stnicture of the 

 starch grain i) has contributed much toward making more generally 

 known just what happens in the swelling of a starch grain. This has 

 been very well described in an earlier communication by Fritz- 

 SCHE 2) in 1834, and in the well-known monograph of C. Nageli 3) in 

 1858 (Beijerinck did not know of the observations of these investi- 

 gators on this subject) , and also, in 1 908, Mme. Z. Gatin-Gruzewska '^) 

 had a correct conception of the process, but the simple experiment 

 with which Beijerinck elucidated the swelling process is so con- 

 vincing that the descriptions given by earlier investigators have be- 

 come of much less importance. This experiment consists of the addi- 

 tion of a solution of tannin to a suspension of swollen starch grains, 

 through which a precipitate is formed inside the starch blisters which 

 shows a Brownian movement. This last f act, especially, removes all 

 doubt as to the liquid nature of the contents of the blisters. 



A later short study of Beijerinck on "Crystallised Starch" 5) won 

 less recognition, and the writer is not wholly convinced that what 

 Beijerinck considers as "starch crystals" should not in reality be 

 taken as amylodextrin (in Walter Nageli's sense ^)). Yet, the 

 several Communications, and especially the accompanying micro- 

 photos, are interesting. 



It is needless to say that Beijerinck's microbiological investi- 

 gations led him to make himself thoroughly familiar with the proper- 

 ties of the gels, which he used as solid nutriënt media for micro- 

 cultures, and very often also for experiments with enzymes. This ex- 

 plains why Beijerinck brought out also a few publications dealing 

 with subjects which one would not expect to have interest for him. 



In the "Zeitschrift für physikalische Chemie" 7) of 1889 there ap- 



1) Structure of the starch-grain, Proceedings of the Section of Sciences, Kon. Aka- 

 demie van Wetenschappen Amsterdam 14, 1107-1110, 1912 [Verzamelde Geschriften 

 5, 21-24). 



2) J.Fritzsche, CberdasAmylum, Annalen der Physiku. Chemie 32, 129-160, 1834. 



3) C. Nageli, Die Starkekörner, Zürich 1858. 



*) Z. Gatix-Gruzewsk.\, Sur la composition du grain d'amidon, Comptes Rendus 

 de l'Acad. des sciences 146, 540-541, 1908. 



5) Proceedings of the Section of Sciences, Kon. Akademie van Wetenschappen Am- 

 sterdam 18, 305-309, 1915 (Verzamelde Geschriften 5, 195-198). 



«) W. Nageli, Bsitrage zur naheren Kenntnis der Starkegruppe, Leipzig 1874. 



T) 3. Band, 110-112, 1889 {Verzamelde Geschriften 2, 237-238). 



