66 PROTOPLASM. 



Is a Tissue living because attacked to a Living 



Organism ? 



Some appear to think that a change in position only will 

 make all the difference as regards the proper application of 

 the term vital, and seem to hold that a tissue should be 

 called alive as long as it remains attached to a living body, 

 dead when detached, irrespective of changes occurring in the 

 tissue itself. But it is obvious that a leaf, or an elementary 

 part, may be as devoid of life while it remains attached to 

 the living trunk as after its connection with it has been 

 completely severed. To say that a dead leaf exhibits life as 

 long as it hangs on to the branch would be absurd, because 

 differences of a much more important character proclaim 

 whether the leaf be alive or dead, irrespective of its con- 

 nection with the tree. 



Not long ago, it was stated that a living thing might 

 spring from a dying or dead one, as a fungus from a dead 

 elm, by mere transference of force from the latter to the 

 former, that the departing life-force of one thing became 

 transformed into the life of the new one. 



Chemical and Mechanical Changes in Living Beings. 



Neither should changes which are admitted to be me- 

 chanical and chemical, when they occur in the laboratory, be 

 called vital, merely because they take place in a living 

 organism. It is the nature of the change alone which 

 determines its vital or non-vital character. But the term 



