48 ILLINOIS ACADEMY OF SCIENCE 



best be put by a quotation from Hober ( 1 ) * : "Biology experi- 

 ences extraordinarily valuable stimuli as soon as many of its 

 old problems are considered from the standpoint of colloidal 

 chemistry. Consequently every attempt, in any degree possi- 

 ble, to interpret those problems, hitherto not completely under- 

 stood, into colloidal processes is not only desirable but to be 

 demanded. The materials of the biologist offer sufficient rea- 

 son for this. For the microscopist must daily consider colloids, 

 when he deals with the effects of fixing, macerating, and stain- 

 ing reagents upon the structures of protoplasm, for visible 

 evidence of these effects rests mainly upon the visibility of 

 solid or precipitated colloids; the medical chemist deals par- 

 ticularly with colloidal albumin bodies : whoever undertakes 

 problems of metabolism finds that most of his riddles are bound 

 up, in a large measure, with colloidal ferments and any one 

 who undertakes in these days the analysis of any fundamental 

 physiological phenomenon will observe that it is not in vain 

 that protoplasm consists largely of colloids, that all of the 

 more delicate and grosser membranes, which serve for the iso- 

 lation and regulation of biochemical processes, are colloidal 

 membranes. It may be emphasized that a study of immunity 

 reactions presupposes a knowledge of colloidal properties, since 

 toxins, antitoxins, alexins, agglutinins and lysins are colloids." 



II COLLOIDAL NATURE OF LIVING CELLS 



The structure of the protoplasm, its organs and the parts 

 produced by it, has been the phase of biology of perhaps most 

 general interest to which the knowledge of colloids have con- 

 tributed. The students of colloids are coming more and more 

 to view the protoplasm and its individual organs as typical 

 hydrosols or as hydrogels, and it must be acknowledged that 

 they are accumulating much evidence for this conception. 

 From this viewpoint the following are the more prominent of 

 the questions worked upon. In how far are the structures of 

 the cell and its accessory parts hydrosols and how far hydro- 

 gels ? What are the structure of gels and sols in general, in- 

 cluding the protoplasmic gels and sols? Are colloidal struc- 

 tures complex enough to satisfy the demands of protoplasmic 

 processes. 



In answering the first question Czapeck (2) states that cell 

 membranes, gums and starch grains are gels, as well as a num- 

 ber of protoplasmic organs, such as nuclei and many chrom- 

 atophores. 



•Figures in parenthesis refer to the bibliography at the end of this paper. 



