[macallum] cellular OSMOSIS AND HEREDITY 13B 



It must also be postulated that of ithe so-called colloid substances wlidch 

 are formed by, or are the products of, tissue and cellular activity, there 

 are none that are insoluble in the fluids batliing such tissues or cells or 

 in the intrax?ellular fluids. To expi-ess it in another way, the reason 

 why substances which are concerned in tlie vital process circulate and 

 diffuse in tissue elements is that the physiological fluids, extracellular 

 «as well as intracellular, are so composed as to dissolve them. 



To return to Kalilenberg's observations, it may be pointed out that 

 while he was not the first to use nibber membrane as septa for osmotic 

 experunents, since Flusin, Eaoult, Tamman and otiliers had done tliis 

 before him, he w^as the first to investigate thoroughly the properties of 

 Buch rubber septa and to ind^jate the significance of the results. 



One may not detail fully the results of his observations, and I must 

 ask those who are interested in the study of osmosis to consult the 

 original paper, for it is replete with descriptions of experiments which 

 illustrate osmotic phenomena which caimot be obtained ^ith parchment 

 septa and which help to clear up the chief difficulties experienced in the 

 past in; attempts at explaining physiological osmosis. I shall here give 

 only a few details to illustrate the significance of Kahlenberg's results. 



In the: first place, he found that the composition of the membrane 

 is a decisive factor in osmosis. He used in his experiments amongst 

 other membranes septa of pure rubber and various fluids avs solvents, but 

 the most striking results were obtained with pyridine. With pyiiidine 

 cnly on one side of the septum, but with the same medium containing 

 «ane sugar and copper oleatc on the other, it was foimd that the colloid, 

 /copper oleate, freely passed through the septum, but the crj^stalloid,. 

 cane sugar remained behind. On the other hand, two crystalloids, 

 camphor and cane sugar in solution in the pyridine, the camphor, but 

 not the cane sugar passed through the membrane. Here, two ci"}'s.talloids 

 were separated from each other by osmosis. Further, Kahlenberg, as 

 he stated in an address delivered to the chemical section of the American 

 Association during its last session, has been enabled by this method to 

 separate two colloids from each other. 



The rubber membranes in Kahlenberg's experiments were not whoUy 

 impervious to sugar, for traces of it passed through them and so also 

 did nitrate of silver and lithium chloride, but in very much smaller ]-)ro- 

 portions than in the case of cane sugar. That means that tlie non-elec- 

 trolyte sugar diffuses through the membrane more readily than either of 

 the electrolytes. 



When, instead of rubber septa, which he found permeable to copper 

 oleate in benzene, he used a parchment septum with benzene on one side 



