1883.) The Polar Organization of Animals. 493 
halves connected in the median line. The longitudinal polarity 
is little less evident. The human body is an elongated, irregu- 
larly oval mass, branching at each extremity into limbs which are 
_ fundamentally similar. The body forms a hollow cylinder, being 
penetrated by a cavity which is devoted to digestion. Typically 
itisa symmetrical cylinder, but its internal symmetry has been 
broken by the requirements of the digestive function. The meso- 
dermal arrangements do not detract from its symmetry. The 
bones and muscles answer to each other longitudinally. The 
excretory organs display a certain symmetry of arrangement, the 
kidneys for the excretion of liquid waste posteriorly, and the 
lungs for the excretion of gaseous waste anteriorly. Of the two 
remaining sets of organs, the vascular and the nervous, they 
seem, while generally related to the body as a whole, specially 
related to its polar regions. The vascular system, while engaged 
in the general duty of conveying nutriment and removing waste, 
ar the special duty of elaborating germinal products and deposit- 
‘ ing them at the posterior, reproductive pole. The nervous sys- 
: tem, while conveying motor influences to and from the tissues 
i generally, is specially engaged in conveying motor impressions to 
| thebrain, the seat of the anterior or mental pole. 
These poles answer to each other. They differ in organization 
5 from their great difference in use, but they are seated in the oppo- 
; nities of the body, while the special sense organs are 
4 Y contiguous to the nervous pole, and the organs of food ` 
bee n lie in the vicinity of the reproductive pole. And as 
a aea that these poles are not directly but only secondarily 
“hed in the operations of the body, we have the fact that the 
j “ag the reproductive organs may be both removed from 
: can be » and its vital functions continue. In such a case there 
Dià no reproduction, either mental or physical, no offspring, 
tal is a an animal, yet the life of the animal as an individ- 
2 Time necessarily affected, and may be long continued. 
’ though ages are, to say the least, curious, and they extend, 
: Me or less masked, through the whole animal kingdom. 
ae as mae tribes the polarities have not yet become de- 
2 but a prema They are still vague and general, and have 
igo a uence over the form of the body. Hence the 
o ower animals are very largely molded by exterior 
Their bilateral and their longitudinal symmetries are~ 
EIN: ag N eS a een ae ee ree a 
ae 
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