SOME MORPHOLOGICAL RELATIONSHIPS OF THE CACTACEiE. 
BY C. P. MAXWELL. 
Bead November 16, 1894. 
Some time ago I discovered that seedling Cactaceae did not at once 
assume the characters exhibited in the adult form, and the idea was con¬ 
ceived that in this fact might lie concealed some evidence concerning 
the true relationships of the genera of the group, or of the group itself 
to other plants; so some experiments were made by germinating seed of 
some of the genera and observing the changes of form. Living in a re¬ 
gion where the cactaceae are indigenous, many instances of young seed¬ 
lings were found in the natural condition, and all have agreed with the 
results set forth in this paper. 
The observations do not make a complete series, still there is enough 
to make some important suggestions; and while these are given, the hope 
is indulged to carry on the work in future. 
It seemed to me from the start very peculiar that such changes should 
occur in a growing seedling, and the analogy to animal embryology, 
though it occurs in post-embryonic life, is so strong as not to be over¬ 
looked. 
The genera studied so far have been Cactus (Mammillaria, Haw.,) 
Echinocactus, Cereus, and Opuntia. The seedlings have at first practic¬ 
ally the same form in all; 
and its essential features are 
a somewhat conical body, 
point down wards,from which 
originate rootlets, the upper 
part terminating in two tu¬ 
bercular projections,between 
which is the growing point. 
Fig. 1, i. These tubercles 
remind one of cotyledons, 
and though they may bear some relation to them, as subsequent tubercles 
probably do to true leaves, still there is no reason except superficial 
appearance for regarding them as other than projections of the stem. 
They are the embryonic tubercles. 
The growing point is indicated at first by only a few soft hairs, but 
soon a tubercle appears bearing the hairs on its summit. Fig. 1, ii. This 
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