6 



ANATOMY FOB NURSES. 



[CHAP. I. 



broken down by the process of oxidation, and removed from the 

 cell, as is added by the process of assimilation. Chemical 

 changes which involve the building up of living material within 

 the cell have received the general name of anabolic changes ; 

 those, on the other hand, which involve the breaking down of 



such material into other and 

 simpler products, are known 

 as katabolic changes : while the 

 sum of all the ana- and kata- 

 bolic changes which are pro- 

 ceeding within the cell are 

 spoken of as the metabolism of 

 a cell. These chemical changes 

 are always more marked as the 

 activity of the cell is promoted 

 by warmth, electrical or other 

 stimulation, the action of cer- 

 tain drugs, etc. 



(3) The most obvious phys- 

 ical changes which can be seen 

 in living protoplasm, by the aid 

 of the microscope, are those 

 which are termed "amoeboid." 

 This term is derived from the 

 fresh water amoeba, which has 

 long been observed to exhibit 

 spontaneous changes of form, 

 accompanied by a flowing of its 

 soft semi-fluid substance. By 

 virtue of this property, the cells 



FIG. ?>. A TO tf, CONSECUTIVE STAGES can move from one place to an- 

 OF CELL-DIVISION, WITH INDIRECT DIVIS- . TJ , . . ,, , 



ION OF THE NUCLEUS. (Diagrammatic.) other. It one ot these cells be 



observed under a high power 



of-ii microscope, it will be seen gradually to protrude a portion 

 of its protoplasm ; this protrusion extends itself, and the main 

 part or body of the cell passes by degrees into the elongated 

 protrusion. By a repetition of this process, the cell may glide 

 slowly away from its original situation and move bodily along 

 the field of the microscope, so that an actual locomotion takes 

 place. When the surface of these free cells comes in contact 



