2. The Production or the DISE.\^■.E. 



If we have said that we must begin with the individual cells when judg- 

 ing a disease, we must know first of all how complicated an organism the cell 

 is and how its structure and function depend on the constitution, position 

 and action of the micellae composing it. 



Let us, for example, examine some effects of "swelling." The cell wall 

 at a given time is saturated to a definite degree with water of imbibition, that 

 is, the cellulose micellae held together by cohesion are provided with a water 

 sheath with a certain amount of distention. The micellae will be separated 

 further from one another or will approach one another more closely as the 

 water supply varies; that is, the walls will sometimes become more dense, 

 sometimes more flaccid. Such fluctuations are brought about in the protoplasm 

 of the cell by the action of substances which withdraw water osmotically. 

 Similar processes are observed in chloroplastids, for example, in grain leaves 

 if acted upon by weak chlorin fumes or by sulfuretted hydrogen. The chlo- 

 roplasts are seen to shrivel with the use of chlorine while the chlorophyll 

 (jrains become pale green, doughy, almost gelatinous bodies with sulfuretted 

 hydrogen. 



In the cell wall, marked phenomena of flaccidity may often be restricted 

 to single spots. The so-called "bead-cells" in winter grain may be taken as 

 examples of this. Individual cell groups near the larger vascular bundles 

 show bead-like convex centres of flaccidity on the inner side of their walls, 

 which later lose their cellulose character. If young, vigorously growing 

 potato stems are exposed to frost, difl^erent groups of leaf parenchyma cells 

 will be found later whose walls seem swollen in lines to four times their 

 normal thickness. In this may be observed the browning and decay of the 

 niore dense wall lamellae into stripes which lie imbedded in a homogeneous, 

 lighter parenchyma. 



In the case of very flaccid membranes, however, molecules will be able 

 to penetrate the greatly enlarged micellar interstices, which cannot force an 

 entrance through the smaller ones, because of their size. If changes in the 

 constitution of the protoplasm have been caused by frost, we find substances 

 passing in and out which could not have been transferred before by the 

 plasma body. The red coloring matter and the sugar in frosted red sugar 

 beets (Beta) pass easily from the parenchyma of the beet into the surround- 

 ing water. This would be impossible in the cut beet, if it had not been 

 frosted previously. The loosening of the structure of the organic substance 

 is a very normal process the intensity of which depends on the action of ex- 

 ternal factors, such as water supply, light, warmth, etc. If these normal 

 processes exceed a certain limit, they lead to disturbances which so alter the 

 structure and function of the cells that they become unable to maintain life. 

 Every other process of cell life may be similarly affected. Under the influ- 

 ence of different factors of growth, the process may be hastened or retarded. 

 We know that each life function oscillates between wide limits, according to 



