CYTOMORPHOSIS II 



its protoplasm may be infiltrated with fat and appear vacuolated. It 

 may form abnormal intercellular substances, for example, amyloid; or 

 the existing intercellular substances may become changed to mucoid 

 masses, or have lime salts deposited in them. Thus an impairment or 

 perversion of function is often associated with optical changes in the cell 

 substance. 



The removal of dead cells is accomplished in several ways. Those 

 near the external or internal surfaces of the body are usually shed or des- 

 quamated, and such cells may be found in the saliva and urine. Those 

 which are within the body may be dissolved by chemical action or de- 

 voured by phagocytes. 



Every specimen of human tissue exhibits some phase of cytomorphosis. 

 In some sections a series of cells may be observed from those but slightly 

 differentiated, to those which are dead and in process of removal. Because 

 of the similarity and possible identity of this normal "physiological" 

 regression, with that found in diseased tissues, such specimens should be 

 studied with particular care. 



VITAL PHENOMENA. 



The vital properties of cells are fully treated in text-books of physi- 

 ology. They include the phenomena of irritability, metabolism, con- 

 tractility, conductivity, and reproduction. Under irritability may be 

 grouped the response of cells to stimuli of various sorts, such as heat, light, 

 electricity, chemical reagents, the 

 nervous impulse, or mechanical inter- 

 ference. Metabolism, in a wide sense, 

 includes the ingestion and assimila- 

 tion of food, the elaboration and 

 secretion of desirable products, to- 

 gether with the elimination of waste " 6 8 10 Minut " 



, .-, iVi u FIG. 10. LEUCOCYTES OF A PROG. X 560. 



prodUCtS. Contractility may be Changes in form observed during ten minutes; 



manifest in the locomotion of the 1 1 



entire cell, in the vibratile action of 



slender hair-like processes, the cilia, or in contraction of the cell body. 

 Conductivity is the power of conveying impulses from one part of the 

 cell to another. Reproduction is seen in the process of cell division. 

 Many phases of these activities are observed in microscopic sections and 

 as such they will be referred to in later chapters. A few which are of 

 general occurrence will be described presently. 



AMOEBOID MOTION. 



The unicellular animal, Amoeba, exhibits a type of motility known 

 as am&boid, which has been observed in many sorts of cells in the verte- 



