ALTERNATION OF GENERATIONS IN ANIMALS FROM 
A BOTANICAL STANDPOINT.? 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY. 
CHARLES J. CHAMBERLAIN 
(WITH TWO FIGURES) 
SINCE zoologists do not recognize in animals an alternation of 
generations comparable with the alternation of gametophytic and 
sporophytic generations in plants, it may seem presumptuous for a 
botanist to propose any theories. Nevertheless, after hesitating for 
several years I have decided to publish my belief that animals exhibit 
an alternation of generations comparable with the alternation so 
well known in plants. 
In short, the theory is this: the egg with the three polar bodies 
constitutes a generation comparable with the female gametophyte in 
plants; similarly, the primary spermatocyte with the four sperma- 
tozoa constitute a generation comparable with the male gametophyte 
in plants. All other cells of the animal constitute a generation com- 
parable with the sporophytic generation in plants, the fertilized egg 
being the first cell of this series. 
In support of this theory I shall present two lines of evidence: 
(1) the gradual reduction of the gametophyte in plants, with the 
constantly diminishing interval between the reduction of chromosomes 
and the process of fertilization; and (2) the phenomena of chromatin 
reduction in both animals and plants. 
1. EVIDENCE FROM THE REDUCTION OF THE GAMETOPHYTE IN 
PLANTS.—For convenience, the female and the male gametophyte 
will be considered separately. Further, since dioecism in gameto- 
phytes is regarded as a more specialized condition than monoecism, 
and since the tendency is toward dioecism, all cases in which the 
gametophytes have not attained the dioecious condition may be 
disregarded. 
* Presented before Section G of the A. A. A. S., at the Philadelphia meeting, 
December 30, 1904. 
905] 137 
