PROPERTIES OF PROTOPLASM 3 



growth and reproduction. In addition, protoplasm pos- 

 sesses in great degree the power of movement as well as 

 of perception. Motion is not always evident but in cer- 

 tain stages at least it can almost always be found. The 

 protoplasm may move as a whole or certain portions of 

 the cytoplasm may stream to and fro in a most compli- 

 cated manner. Such streaming may affect only the small 

 granules, or the larger bodies such as nucleus and plastids 

 may be transported from one place to another. 



5. Protoplasm possesses the power of imbibition of 

 water. It may imbibe so much water that it becomes 

 very thin and watery and yet still retain its powers of 

 motion and of reproduction. There is a limit, however, 

 to the amount of water protoplasm will imbibe, for some 

 of the naked masses of protoplasm set free by some 

 plants for reproductive purposes retain their shape and 

 size in spite of being immersed in water. 



6. The complex chemical and physical structure of 

 protoplasm renders it very susceptible to injur}'-. This 

 injury may be simply physical, or certain of the groups 

 of atoms making up the complex protoplasmic molecule 

 may be changed chemically in such a way that the proper 

 functions can not be carried on. When the changes reach 

 such a point that on removal of these external unfavorable 

 conditions the protoplasm does not resume its functions, 

 we say that death has occurred. Heat, cold, electricity, 

 even light, also mechanical injury such as crushing, as 

 well as innumerable chemicals will cause death. Many 

 of these agents when applied in smaller amounts or to 

 a lesser degree check the functions of protoplasm only 

 temporarily. Thus a jar or sudden cooling will check 

 for a time the streaming within the protoplasm. 



7. All of the modifications of protoplasm are, at least 

 when active, in a more or less liquid state. The two 



