Alternation of Generations in Radiata. . ita 
8. The diurnal variations of the erica ‘magnetic intensity 
are, for the most part, in accordance with the idea that they arise 
from variations in the difference between the temperature at> the 
¥ station of - needle and the temperature af. a place. to the nee 
k or south of i 
The al variations of ‘vertical force and “ietene of. sone 2 
* perature also appear to proceed pari passu with each’ other; but 
» . the observations hitherto discussed are too lithited to settle defini- 
tively the question of natural dependence. © 
9. There is an undoubted connection bagween the diurnal 
variations of the declination and those. of the horizontal force. . 
his connection may be described as: follows # ‘when: the curve 
iar oy l ‘variations ‘of the horizontal ‘force is concave 
be 
cotemporaneous vie the points of inflexi ion. of the curve of 
[ 3 horizontal force.* 
ae 0. 
. hich the declination varies with the shifting’ posit “the 
ual molecular magnetic intensity ;—which tie. wii Beret 
aly coincident with-the line of equal horizontal” mag 
ce. ‘The line in question differs from wee true ithe ut | 
; Teason. of the oe of the horizontal fore 
“thon in Planis and tie Alternation of Generations” observ 
“tn gome. Radiata ; by, Janes. D. Dan NA. 
af Boat etre the Airican Ascovation for we Advancement of Science at New 
n, August, 1 
: Tur very ‘eoiplikable fact that a Polyp and a Medusa may be 
N some instances different states of one and the same species, 
} been well established of late by the researches of Sars, 
yell, Steenat trap, and others; and recent important observa- 
* See this Journal, 2nd ser., viii, 360, 361. 
ion ( westerly) is increasing; and when the 
This connection accords with.our theory, agreeably to 7 
aa, the. (edu 5 between the mode of Rep: epreditt 
