Nature of the Semi-permeable Membranes. 129 



died immediately after the injection, three lived longer than three 

 hours, i. e., between 3 and 20 hours (died in night), one lived 

 eighteen, one twenty-three, and one thirty-six hours; one lived 

 two days, one nine and one 16 days, and six rabbits survived. 

 The meaning is quite unmistakable; the injection of sodium 

 iodid undoubtedly reduced the mortality or postponed death in a 

 palpable manner. We may add that the favorable effect of the 

 iodid seemed to be more manifest in white than in gray rabbits. 



The experiments seem to demonstrate also that sodium iodid 

 antagonizes essentially the tetanic effects of morphin, while the 

 depression is perhaps even more manifest in the iodid animals. 

 However, we shall not discuss these particulars for the present. 



We experimented also with mice. For mice we can only say 

 for the present that iodid seems to retard perceptibly the onset 

 of convulsions and the fatal outcome of morphin poisoning. 



85 (78i) 



On the nature of the semi-permeable membranes which surround 

 the fibers of striated muscle. 



By Edward B. Meigs. 



[From the Wistar Institute 0} Anatomy and Biology.] 

 The view that the fibers of striated muscle are surrounded by 

 semi-permeable membranes has received a wide acceptance among 

 physiologists, and there has been a good deal of speculation re- 

 garding the nature of these membranes. The hypothesis that 

 they are composed of lipoids has received much attention. Arti- 

 ficial lipoid membranes, however, have been found to be either 

 ^permeable both to water and to dissolved substances or else 

 nearly equally permeable to water and to dissolved substances. 

 It is a general rule that artificial membranes composed of pure 

 colloids are either impermeable to both water and dissolved salts; 

 or else nearly equally permeable to water and salts, and imper- 

 meable only to colloids. The best known artificial membranes 

 which are semi-permeable with regard to salts dissolved in water 

 are composed of precipitates of insoluble salts such as copper 

 ferrocyanide and calcium phosphate. 



