Biological Papers. 



347 



and four functional spores capable of producing male gametophytes 

 are produced. In most of the higher plants the former is a mega- 

 spore and the latter are microspores. The cycle for plants is com- 

 pleted when the megaspore germinates and produces a female 

 gametophyte, 5, 5, which bears an archegonium containing, when 

 it matures, an egg, and the microspores germinate and develop into 

 male gametophytes, 6, 6, bearing antheridia containing at maturity 

 the sperms ; 7 and 7 are merely fertilized eggs, like 3 and 4 at the 

 left in diagram Y, the upper 7 for animals and the lower 7 for 

 plants. 



Weismann invented his hypothesis respecting the continuity of 

 germ-plasm to combat the hypothesis of Lamarck that acquired 

 characters are inherited. Weismann contended that the cells of 

 the body may be grouped into two classes, the soma- or body-cells 

 and the germ-cells. He declared that the soma-cells might be 

 modified by use, but such modifications could not be transmitted 

 to offspring, for the germ-cells would remain unmodified. 



This ingenious hypothesis was at once attacked by the Lamarck- 

 ians and Neo-Lamarckians, and Weismann added biophors and 

 determinants to his germ-plasm to strengthen his position. 



Many mathematical biologists have accepted Weismann's views 

 respecting heredity, and have declared that Lamarckianism is dead. 

 If they are right, it is very strange that the disciples of Weismann 

 are obliged to repeat their declaration so frequently. 



The two main assertions of Weismann have not been proved. 



