84 



peared a short communication "Ein einfacher Diffusionsversuch", in 

 which BEIJERINCK describes how on the diffusion of a drop of acid 

 placed on a 10 per cent gelatine gel, there appears a depression in the 

 gel at the limit to which the acid has spread. Using this technique, 

 BEIJERINCK was able to make several observations, viz., the diffu- 

 sion velocity could be studied and measured under the microscope, the 

 liberation of hydrochloric acid due to hydrolysis of ferric chloride, and 

 other observations. 



A communication of a colloid chemical nature which appeared in 

 1896 in the "Centralblatt fur Bakteriologie, II. Abt." ') was, in fact, of 

 special significance. In this publication BEIJERINCK describes a few 

 experiments with soluble starch obtained by him from potato starch 

 by treatment with hydrochloric acid, and which he used often in his 

 experiments with amylase. It appeared now to him that a solution of 

 this starch in water cannot be mixed with a solution of gelatine to a 

 clear solution, but that the mixing of the two results in an emulsion. 

 By cooling the mixtures of solutions of starch and gelatine in certain 

 proportions, he was able to obtain solid mixed gels, which could be 

 called "kunstliche Zellgewebe". The walls of these "spurious tissues" 

 consisted of either starch gel or of solidified gelatine, according to the 

 proportions used. 



O. BUTSCHLI mentions these observations of BEIJERINCK in 1898 

 on page 251 of his well-known work "Untersuchungen uber mikrosko- 

 pische Strukturen" 2 ), with these words: "Dieses fiir zwei wasserige 

 Losungen sehr eigentumliche Verhalten, dass mir, offen gestanden, 

 wenig wahrscheinlich vorkam, konnte ich zu meiner Ueberraschung . . 

 . . . bestatigen." 



In 1910 BEIJERINCK further described the observations just 

 mentioned, and added some similar ones. This time his publication 

 appeared in the "Kolloid-Zeitschrift". We mention here, by the way, 

 that BEIJERINCK had in the meantime observed the same phenomen- 

 on, which he described in 1896 for solutions of soluble starch and 

 gelatine also for mixed solutions of gelatine and agar. We further 

 mention that BEIJERINCK defends the conception, in his final consider- 

 ations, that emulsion-colloids may not be considered simply as 

 droplets of a dispersed phase in a liquid. The final sentence of his 

 publication reads therefore: "Und wenn es sich herausstellen sollte, 

 dass die Eigenschaften der "Emulsionskolloide" nur erklart werden 

 konnen, wenn man annimmt, dass die Losungen derselben aus kleinen 

 wasserhaltigen Substanzmengen bestehen, welche im Dispersions- 

 mittel schweben, dann miissen diese Substanzmengen derart charak- 



]) Ober eine Eigentiimlichkeit der loslichen Starke, Centralblatt fiir Bakteriologie 

 und Parasitenkunde II. Abt., 2, 697-699, 1896 (Verzamelde Geschriften 3, 187-188). 



>) Leipzig 1898. 



3 ) Ueber Emulsionsbildung bei der Vermischung wasseriger Losungen gewisser 

 gelatinierender Kolloide, Kolloid-Zeitschrift 7, 16-20, 1910 ( Verzamelde Geschriften 



4f-t t * ,-1 A r\ X ' 



, 341-347j. 



