61 



according to Enriques, the gut of very large animals does 

 not contain much more than 10 c.c. In that way Cohnheim 

 must have made his experiments on distended guts. This is ac- 

 cording to Enriques one of the chief sources of error in his 

 experiments: the epithelium after death has allowed the contents 

 to be pressed out through small holes by the surviving muscu- 

 lature. He himself seems to be conscious of this pressure, for 

 he says (p. 24) : „Ich ftillte ihn (i. e. den Darm) unter geringem 

 Druck aus einer Biirette". 



Cohnheim finds that if sea water is put both inside and out- 

 side the gut, it is resorbed almost completely within 24 hours. 

 Enriques does not fill the guts with as much liquid, and 

 does not find any such resorption. 



This discrepancy is rather striking and surely proves that one 

 of the authors must have made more or less serious mistakes. 

 Enriques warns against using the guts for 24 hours or lon- 

 ger, they frequently fall to pieces after that length of time. 



Other experiments have been made both by Cohnheim 

 and by Enriques on the resorption of various substances 

 dissolved in the sea water. Some of Cohnheim's experiments 

 are very unnatural : e. g. he injects a 1 "/q solution of sodium 

 iodide in sea water and a ^/^ "/q solution of sodium phosphate. 

 Experiments of this kind can not possibly elucidate as impor- 

 tant a question as the present one. His results are nevertheless 

 remarkable, he finds that from such hypertonic solutions the 

 dissolved substance as well as the solving medium passes to 

 the outside. 



This is almost pure resorption as we find it in vertebrates 

 and of substances which, if not toxic, are certainly indifferent. 

 On the other hand these salts are used in concentrations which 

 are much too high and their toxic action may easily have kil- 

 led or harmed the gut wall. 



The experiments of both authors on the resorption of 

 sugar etc. also contradict each other in many points and it is hardly 

 possible to get a clear and unprejudiced picture of the process. 



Enriques severely critisises Cohnheim's work and shows 

 many contradictions in his experiments. In some of these ex- 

 periments Cohnheim uses solutions the osmotic pressure ot 

 which is much too high. Sugar solutions in sea water are used 

 e.g. of 3— 18°/o. Such solutions are beyond the range of phy- 

 siology and results obtained therewith only give an insight in 

 a „pathological physiology", as Enriques calls it. Against such 

 osmotic potentials no semipermeability of the gut-wall can resist. 



In the experiments on sea urchins too serious operations are made ; 

 since they gave the same result of those on the cucumbers, I will not 

 discuss them here. 



The outcome of the differences in their experimental results is 



