130 



Scientific Proceedings (53). 



The animal body can present the conditions necessary for the 

 precipitation of calcium phosphate, as, for instance, in the case of 

 bone formation. The striated muscle fibers contain considerable 

 amounts of dipotassium phosphate, and are surrounded by lymph 

 which contains calcium chloride, so that it is far from incon- 

 ceivable that thin layers of calcium phosphate might be precipi- 

 tated at the surfaces of the muscle fibers. 



I have examined some of the properties of celloidin membranes 

 impregnated with calcium phosphate. Celloidin membranes free 

 from precipitate are quite permeable both to water and to dis- 

 solved salts. Such membranes were filled with a dipotassium 

 phosphate solution and immersed in a calcium chloride solution. 

 Under these circumstances they become impregnated with calcium 

 phosphate, and at the same time they become markedly semi- 

 permeable with regard to salts dissolved in water. That is to 

 say that if they separate salt solutions of different osmotic pres- 

 sures, water passes rapidly from the less concentrated to the more 

 concentrated solution. 



Celloidin membranes impregnated with calcium phosphate 

 were filled with a 1.3 per cent, solution of dipotassium phosphate 

 and immersed in isotonic solutions of various substances: it was 

 then determined whether or not water passed through the mem- 

 brane from the outer solution to the inner one against a moderate 

 hydrostatic pressure. Such experiments were tried with solutions 

 of NaCl, KC1, CaCl 2 , cane sugar, alanin (an amino acid), glycerine, 

 urea, and ethyl alcohol. The results indicated that the membranes 

 were highly impermeable to salt, sugar, and amino-acid, somewhat 

 permeable to glycerine and urea, and highly permeable to ethyl 

 alcohol. In all these respects they resemble the muscle membranes 

 with the possible exception of the case of KC1. There is some 

 reason to believe that the muscle membranes are more or less 

 permeable to KC1. 



The supposition that calcium phosphate plays a part in giving 

 to the muscle membranes their semi-permeable properties would 

 explain two great classes of facts — those facts, namely, which 

 show that muscles rapidly lose their semi-permeable properties 

 in acid solutions; and those which show that calcium may play 

 an important part in maintaining the semi-permeable properties 



