216 PROTOPLASM 



penetrating more deeply into the subject, that these obser- 

 vations were even of a kind to furnish additional proofs 

 for the correctness of my theory. 



The Nature of Colloid Bodies l 



The problem of the nature of coagulated albumen and other 

 coagulated colloids must now receive, as has already been pointed 

 out above, quite a different solution from me from that which 

 I gave at the time of completing this manuscript (summer of 

 1891). At that time I had not myself accurately investigated 

 this subject, as I also remarked. Since, however, it is an especi- 

 ally important one, I attempted to obtain more detailed informa- 

 tion upon this point after concluding the present work. That 

 this has not been done till now is scarcely a matter to be 

 regretted by me, but rather to be regarded as a fortunate 

 circumstance, for I think that, probably, all the investigations 

 communicated in the present work would have been left undone 

 if I had taken this question in hand earlier. 



To be brief, the result of the investigations hitherto under- 

 taken by me upon the nature of coagulated white of egg, and 

 of coagulated commercial gelatine, is, that they present all the 

 phenomena which ice have recognised in this work as characteristic of 

 the structure of a fine foam. I will not describe my experiments 

 and observations more in detail in this place, since it will be 

 necessary to bring them out later more fully, and accompanied 

 by photographs of the most important relations. I will, only 

 mention that coagulated white of egg and gelatine have a very 

 beautiful, finely honeycombed structure, and since the false 

 reticular image can be seen distinctly with a higher focus, 

 the alveoli possess less refractile contents, probably consisting of 

 a watery fluid in the honeycombed framework. In both the 

 radiate alveolar layer can be plainly made out, both on the 

 surface and round the larger vacuoles of the interior. In all 

 parts which during the coagulation are subject to a pull or a 

 tension, a nbrillated alveolar structure is shown, frequently 

 magnificently developed, and agreeing completely with the 

 corresponding structures of protoplasm. It is also frequently 

 possible to see in the interior of such coagulated masses radiating 

 appearances which quite rival those of protoplasm. 



So far the appreciation of the relations of the coagulation 

 products in question offers no special difficulties for any one who 



1 An addition made by the author in April 1892 after completion of the 

 manuscript. 



