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of the parts of the embryo in the seed; yet the author has ven- 
tured to go farther than anyone before him, and has pointed out 
just how different forms of embryo have originated. This gives 
to the old facts a new charm. As the author informs us on the 
first page, these propositions have already been made in the 
“Jour. Linn. Soc. Vols. xxii.-xxiv.,” and as he now reprints them, 
we feel assured that his confidence in his own interpretation of 
nature is not shaken by subsequent observation and reflection. 
All may not agree with him in his interpretations, but no one can 
question his accuracy of observation. It remains for his critics to 
draw conclusions which will harmonize better with the facts. 
Some of these propositions may be profitably mentioned. 
1. The inversion of the ovule is of advantage to the plant in 
that it brings the micropyle in such a position as to increase the 
probability of fertilization. Here the author confirms the con- 
clusions of others and promises “to enter into the question more 
fully on a future occasion.” The writer of this review has sug- 
gested an entirely different explanation of this modification of the 
ovule and seed, i. e., that it is due to the advantage gained by the 
correlation of the parts of the embryo, to the external appendages 
of the seed, thereby securing a favorable position for the embryo 
during germination. (See “Science Vol. xx. No. 504, September 
30, 1892.”) 
2. Unequal, unsymmetrical, lobed, and auricled cotyledons are 
to be explained by the crowding of the embryo in the seed, and 
its tendency to occupy all the available space within the coats. 
3. The position of the embryo is often changed to accommodate 
its parts to the form of the seed. Embryos with accumbent and 
incumbent parts are, in many cases, thereby explained. «Now 
if from the form of the pods, or for any other reason, it is an ad- 
vantage that the seed should be compressed, then the thickness 
of the cotyledons remaining the same, it is better that the radicle 
should be accumbent; while on the other hand, in a thicker or 
globular seed the incumbent arrangement is most convenient.” 
In general, the author believes that the form of the seed determines 
the form of the embryo. : 
4. It seems desirable that the cotyledons should be raised above _ 
the surface of the ground. This leads to a correspondence between 
the length of the hypocoty] and the length of petiole of the coty- 
