500 



THE 



[TURALIST 



[Vol.L 



gametophyte rests upon the 2s as compared with the x condition 

 of the chromosomes, we find that among animal organisms the 

 asexual phase has actually become the dominant method of re- 

 production and the sexual phase is represented only by the para- 

 sitic cells arising through the reduction division. In accordance 

 with this view one is prepared to accept the spore mother cells 

 of plants as homologues of the cells preceding the reduction di- 

 vision in animals, tn a subsequent discussion Coulter states in 

 accordance with the view first advocated that the animal body 

 produces gametes and not spores. When reduction occurs at the 

 time of the first maturation division in animal organisms it is 

 quite clear that the cells thus produced may correspond to spores 

 which in the next division give rise to gametes. It may even be 

 asserted that they are megaspores or microspores dependent on 

 the sex represented. When chromosome reduction is moved for- 

 ward to the second maturation division, however, it is possible to 

 agree with Coulter, but seemingly more logical to admit that the 

 change is a secondary one and that the first maturation cells may 

 still represent the spore cells. 



In accordance with the proposition that spores unite as gam- 

 etes to form a single cell, evidence should either be presented to 

 show that an identical chromosome composition exists between 

 the actual spores and the so-called spores functioning as gametes 

 or consideration should be given to subsequent reduction division. 

 Otherwise the conclusion scarcely merits the value of an opinion. 

 Furthermore, the argument that the fusion of a sperm and cell 

 among the angiosperms to form a nutritive endosperm justifies 

 the conclusion that pairing and fusing do not represent the es- 

 sential features of sexuality, can not be considered. This is only 

 one of numerous examples where changes in form or function of 

 parts occur without having any bearing on the actual origin of 

 the part. Even in this ease a fusion is represented and may 

 have a value similar to that among gametes. 



It is in connection with "A Theory of Sex" that it seems neces- 

 sary to decidedly differ from Professor Coulter. Here the two 

 main theses are that sexuality has arisen (1) to carry an organ- 

 ism through an unfavorable environment, and (2) to make evo- 

 lution more rapid by presenting a greater diversity of forms. 



The first deduction is based on the proposition that gametes 

 in many plants are produced at the close of the vegetative period. 

 Such a conclusion— post hoc ergo propter hoc— does not rest upon 

 a sound basis. With the fulfilment of a function having the 



