Mutations and Evolution . 
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in the male gametophyte of many Gymnosperms. There is one 
such cell in Cycads, which persists. Ginkgo has one ephemeral 
and one persistent prothallial cell which are cut off in succession 
by the side of the microspore, while in Pinus both prothallial cells 
dwindle promptly to small dark-staining masses, as though the life 
had quickly gone out of them. The nucleus may begin to dis¬ 
organize even before the cell-plate is formed. Such structures 
represent momentary stages of an ebbing tide. It \Picea canadensis , 
Hutchinson (1915) has found all these and other conditions to occur 
as variations. 
Recapitulation in the Sporophyte. 
If now we turn to the sporophyte, we find again many of the 
most striking cases of recapitulation in Gymnosperms. Indeed they 
appear to be of more frequent occurrence in this group than in any 
other plants. A possible reason for this has already been suggested, 
namely the relative infrequency of mutations. It is well to keep in 
mind also that recapitulation in the sporophyte usually indicates 
adaptation to altered conditions. Among well known instances in 
Conifers may be cited the genus Phyllocladus, characterized by an 
absence of leaves, the branches forming flattened leaf-likeexpansions. 
The seedlings, however, have a terete axis bearing ordinary leaves 
and this obviously represents the ancestral condition, from which 
for some unknown reason the genus departed. That such an 
alteration is not mutational is indicated, according to the present 
interpretation, by the fact that the ancestral condition is thus clearly 
present in the earlier stages of ontogeny. A mutational change, being 
represented in every nucleus from the fertilized egg onwards 
would have eliminated, or rather transformed, this juvenile stage. 
In CEnothera, as de Vries (1909) pointed out, the first leaves after 
the cotyledons make it possible to recognize a mutant form. 
To mention threeothercases of recapitulation in Gymnosperms: 
A feature of the genus Pinus is the occurrence of dwarf shoots, 
each bearing a fascicle of needle leaves. But in the seedling the 
leaves are scattered on the stem as in other conifers. Similarly 
the genus Larix, unlike most conifers, has deciduous leaves; but in 
the juvenile stage the leaves adhere for several years. In the 
Mariposa grove near the Yosemite valley in California I observed 
that Sequoia gigantea is a number of years old and many feet high 
before its foliage acquires the characteristic appressed form. When 
grown in the English climate, this appressed type of foliage appears 
never to be quite reached even in old trees. 
