THE COLLOIDAL STATS. $i 



this honeycomb structure is ordinarily not convincingly 

 demonstrable; it becomes distinctly visible, however, 

 under certain experimental conditions. 



A closer study. of the conditions whicri make apparent 

 the honeycomb structure teaches us, however, that we 

 have to deal in every case with the introduction of true 

 coagulation or precipitation phenomena governed by the 

 laws already outlined above. By far the most thorough 

 investigations bearing upon this subject have also been 

 carried out on solidified gelatine, and upon these BUTSCHLI 

 supports in the main his belief in the primary honey- 

 comb structure of all swollen media, and consequently 

 also that of native protoplasm. 



But, as has already been pointed out, even though 

 neither direct observation nor tinctorial methods and 

 this in spite of the well-known marked affinity of gelatine 

 for dyes have rendered it possible to prove the existence 

 of a honeycomb structure in untreated gelatines, such a 

 structure is, nevertheless, supposed to exist in all prob- 

 ability. The reasons which BUTSCHLI has brought for- 

 ward in support of this idea can only very briefly be given 

 here and their tenability be tested. 



The reason why it is normally impossible to see the 

 walls constituting the framework of gelatine is, according 

 to one author, dependent in part upon the fact that they 

 are pliable and when dried in vacuo, for example, adhere 

 closely to each other, in part upon the fact that the 

 difference between the indices of refraction of the walls 

 of the framework and of the substance found within 

 them is too little to give distinct pictures. These walls 

 of the honeycomb structure can, however, be rendered 

 more solid and dense through the action upon them. of 



