286 Causes and Course of Organic Evolution 



But for the Fungi, as for the Algae and Protozoa, we would 

 assert that asexual cells, exactly comparable to akinetes, aplano- 

 spores, and swarmspores in their mode of fonnation and rela- 

 tion, can be set free, and that each accurately reproduces the 

 structure and life role of the parent. In the production of 

 sex cells on the other hand, each cell has been exposed in the 

 parental cell that produced it, as well as in itself, to similar 

 or dissimilar environment, that may produce similar or dis- 

 similar results in formation of each sex cell. Since cross ferti- 

 lization also is frequently between distinct individuals, a con- 

 stant response to, adaptation to, and perpetuation of biotic 

 and cognitic lines of energy flow, as well as of flows of simpler 

 forms of energy, that place, build up, and energize definite 

 material particles, must constantly be proceeding in the sex 

 cells. So the sex cells on fusion must, unless all physical and 

 physiological laws are inapplicable, transmit such exact lines of 

 energy flow, and the exact grouping of particles that these effect. 



Sexuality in Higher Plants. We pass now to the higher 

 groups of plants. Without entering here into the long-dra\^^l 

 question of the origin and significance of alternating gameto- 

 phyte or haploid and sporophyte or diploid generations, from 

 the Algae and Hepaticse upward to the Cycadacese and Gink- 

 goacese, it can vnih. considerable safety be now said that for 

 these, as for many of the previously treated simple plants and 

 animals, a reduction division occurs during the stage of spore 

 formation, so that the sex cells have an amount of chromatin 

 that, in energizing capacity and molecular adjustment, repre- 

 sents for each about half that of a diploid cell. 



Such might explain why, in slow process of evolution, the 

 haploid or gametophyte generation has become gradually 

 reduced in size and \ngor, while the diploid has become increas- 

 ingly enlarged till in the giant redwood tree each sporoj^hyte 

 individual may be at least 1500 years old and 300 feet in height. 

 But it is j)ossible to emj^hasize overmuch the mere number of 

 chromosomes. For tlie num])ers may vary, even in species 

 of a genus, and very strikingly in genera of some families, 

 amongst the higher flowering plants. 



