CHAP, xvm A "FAIRY TALE OF SCIENCE"? 253 



not knowing, and not caring to know, what he means 

 by it. 



In taking leave of Weismann's fairy tale, it may be 

 desirable to name one by one his characteristic posi- 

 tions, and to add in regard to each whether he still 

 retained it in 1893, or had modified it, or had can- 

 celled it. 



First, Weismann used to hold that protozoa and 

 protophyta unicellular nucleated plants and ani- 

 mals, the lowest forms of life known to us were 

 exempt from natural selection, and were subject to 

 the agency of environment as a source of variations. 

 Convinced by the experiments and arguments of 

 other writers that conjugation and natural selection 

 were both at work in these creatures, he has come to 

 postulate still simpler forms of life unknown to ob- 

 servation creatures without even a nucleus 

 creatures (though not the only creatures) which are 

 potentially immortal. Now, it is an immense weak- 

 ness to have to postulate unknown forms of the living 

 organism. Yet perhaps it may be contended that 

 this one addition to the theory is sufficiently logical 

 and coherent. Even in the protozoa and protophyta, 

 as an unscientific person might say, " germ plasm " 

 is hidden away in a nucleus, if not behind the wall of 

 a special cell. In purely homogeneous living organ- 

 isms, if such existed, all parts must share and share 

 alike in the interactions between organism and en- 

 vironment. 



Weismann held that the protozoa and protophyta 

 were potentially immortal; also the germ plasm. All 

 these positions stand, or stood, up to the date of 1893. 



