On Electro-magnetism as a Moving Power. 343 
} larize and allied species; and when it has fully matured, it pro- 
_. duces, like the Medusa, ovules or seed—these seed to begin the 
_ _ found again of successive or alternating developments. a 
ye Thus among plants the seed produce leaf-individuals; these 
Me yield bulbs or buds becoming flower-individuals; and these pro- 
duce seeds; precisely, as the egg produces polyps, the polyps, 
bulbs that develop into Meduse, and the Meduse, eggs." 
When we follow out this subject minutely, we find the -anal- 
ogy completely sustained even in minor points of structure and 
. growth. .The leaf-bud consists of leaves developed in a spiral 
order; and in the polyp, as some species-show beyond doubt, the ~ 
tentacles and corresponding parts are spiral. in development. The. — 
same spiral character is found in the flower, but the volutions are ~ 
the 
t 
Cy 
so close as not to be distinguished readily from circles. In 
Meduse referred to, the regularly circular form is far more neatly 
Med 
: and perfectly developed than among the poly ps—as is clearly seen 
ia comparison of the polyp Coryna, with the elegant Sarsia, a 
ws 
___ fessor Agassiz’s ‘recent memoir, published by the Ameriean 
-. emy.of Arts and Sciences at Boston. The relations in structure 
etween plants and polyps might be farther dwelt upon ;.but for 
ther observations the writer would refer to his’ volume* on 
tae . 
Avr. XXXL—On Electro-magnetism as a Moving Power ; by 
Lae ~~ Prof. Caras. . Pace. 
Na Sa 
+¢. 
G 
cted with the poles of a battery in action, that an iron bar 
a 
: species of which is described and beautifully delineated .in Pro- 
a? : fie Ament 
