334 
The Ohio Naturalist. 
[Vol. V, No. 7, 
Suppose that this spore, on germination,^ fails to reduce the 
chromosomes. The resulting individual will have the double 
number in each cell. Now if, when reduction takes place, the 
cells reduce the chromosomes and the resulting cells are gametes, 
a new condition arises in which a '‘'lx” sexual generation orig- 
inated from an ” x” nonsexual type gives rise to gametes as the 
result of a reduction division. A simple sexual cycle is estab- 
lished with a “'lx” sexual generation producting gametes as the 
result of reduction (Fig. 1 b). Such plants as Fucus must have 
established their life cycle in this way. The Fucus plant is a 
'lx sexual generation wdiich develops ovaries and spermaries. A 
cell in the ovary undergoes the reduction division and by further 
divisions usually produces eight eggs with chromosomes each. 
In the spermaries a cell also undergoes reduction and by subse- 
quent divisions a number of spermatozoids are produced having 
the X number of chromosomes. 
3. The third point at which the reduction division may be 
established is after the sporophyte stage in connection with an 
alternation of generations. Suppose a nonsexual organism 
develops zoospores which conjugate and the zygote fails to reduce 
the chormosomes at the first division. An individual is produced 
with 'lx chromosomes. When zoospores are produced as the result 
of a reduction division they come out not as gametes but as non- 
sexual spores which give rise to an .v generation. This genera- 
tion being similar to the original generation jjroduces gametes 
without reduction which have the % number of chromosomes. This 
is the process in the plants with a true, antithetic alternation of 
generations. A gametophyte generation is followed by a sporo- 
phyte generation which reduces the chormosomes before the 
development of nonsexual spores (Fig. 1 c). 
Other life cycles might be and perhaps are developed. A 
sporophyte coming from the zygote might develop spores with- 
out reduction and these might develop into gametophytes with 
the 'lx chromosomes, and the gametes would then be produced 
as the result of a reduction division (Fig. Id). It will be seen, 
therefore, that there are two types of sexual or gamete-producing 
generations, one with the 2 .t chromosomes giving rise to gametes 
through reduction, the other with x chromosomes giving rise to 
gametes directly without reduction. 
Now in the higher plants the life cycle is invariably estab- 
lished, unless in abnormal cases, with an alternation of genera- 
tions, a gametophyte generation with x chromosomes is followed 
by a sporoi)hyte generation with 'lx chromosomes. The reduc- 
tion division takes place in special cells, sporocytes, and usually 
by two successive divisions. The resulting spores have the 
reduced number of chromosomes and represent the first cell of 
the gametophyte generation (Fig. 2). There is no more reason 
