1040 ELLIOT ROWLAND DOWNING 
hypothesis of the alternation of generations in animals has been 
proposed and vigorously advocated by Beard. He recognizes 
an antithetic alternation of generations in animals. He, too, 
identifies ‘‘the primary germ cells as the equivalents of the spore- 
mother-cells of plants.’”’ He regards the larva or phorozoon as 
the asexual generation, the homologue of the sporophyte. He 
derives the gametozoon, the adult animal, from it by apospory. 
He is forced to conclude, then, ‘‘ that the final reduction of chromo- 
somes has been deferred to a later portion of the life cycle in 
metazoa as compared with plants.” 
The same objections apply to Beard’s hypothesis as to Cham- 
berlain’s, namely, that there is no evidence in fact of the succes- 
sive steps in the postponement of reduction in animals similar 
to that so constantly apparent in plants. So far as we know, the 
process always occurs closely adjacent to the union of the gametes, 
continuing, in the higher animals, in much the same position in 
the life cycle that it occupies in the lower animals and plants. 
Whereas, in plants, it is evidently shifted from this primitive 
position and the successive steps of the shift are traced with some 
degree of certainty in living forms. 
Furthermore, it seems to me, an impossible task to articulate 
his theory with what we know of the reduction phenomena and 
the development of the protozoa and mesozoa. He says: 
The sexual generation of plants is at best a miserable failure from the 
morphological point of view. . . . The higher one ascends the 
smaller it bécomes until in the higher plants it has almost reached the 
vanishing point, without, however, being able to disappear entirely. 
In the animal it is the larva, the phorozoon, or asexual generation 
which makes the bravest show in the lower metazoa; . . . In 
the higher forms it becomes reduced. 
But how will a relation be established between the larva of the 
metazoa and the asexual generation of the protozoa? The one . 
should pass over into the other. It seems unwise to adopt a 
theory which demands a hiatus at this point, when it is easy to 
blaze a possible, uninterrupted trail along which evolution may 
have proceeded by way of such forms as the Volvocales and the 
Dicyemidae, if we adopt the hypothesis I have proposed. 
