THE GERM-PLASM THEORY 91 



are erected into a new family of living beings, the 

 " Biophoridae," and we are told they were spon- 

 taneously generated, and that no man can prove 

 the contrary, for they are, and must always be, 

 invisible. Surely the spinning of theories can go 

 no further than this. 



Even its author at times allows himself to doubt ; 

 for in one place he says and with these wise words 

 we must leave the subject of this book : 



" While dead albumen is certainly nearly allied 

 to living matter, it is precisely life that it lacks ; 

 and as yet we do not know what kinds of chemical 

 difference prevail between the dead proteid and 

 the living ; indeed, we must honestly confess that 

 it is a mere assumption when we take for granted 

 that there are only chemicophysical differences 

 between the two. It cannot be proved, in the 

 meantime, that there is not another unknown 

 power in the living protoplasm, a " vitalistic 

 principle," a " life-force " on the activity of which 

 these specific phenomena of life, and particularly 

 the continually repeated alternation of disruption 

 and reconstruction of the living substance, dis- 

 similation and assimilation, growth and multipli- 

 cation depend " (vol. ii. 369). 



