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ZOOLOGY: E. G. CONKLIN 
before the egg substances have regained their normal positions there is 
usually an abnormal distribution of these substances to the two daughter 
cells and since these substances do not pass through partition walls 
this abnormal distribution persists throughout later development. In 
each of the daughter cells, however, the protoplasm goes to the animal 
pole and the yolk to the vegetative one and the subsequent develop- 
ment is as nearly normal in every respect as is possible, although it is 
not possible to entirely undo the effects of the earlier dislocation. These 
results are in substantial agreement with the earlier work of Morgan 
(1907, '09, '10), Lillie (1906, '09), Conklin (1910, '12), et al., on the 
development of centrifuged eggs of other animals. 
We have in these cases one of the simplest examples of organic regula- 
tion in which the organization concerned is merely the polarity of a single 
cell. The fact that polarity and pattern of organization persist in an 
egg after cytoplasm, nucleus, centrosphere, yolk and practically all 
other visible constituents of the cell have been displaced far from their 
normal positions is most remarkable and mysterious. Is polarity the 
result of some immaterial influence, some 'entelechy,' which like a 
divinity 'shapes our ends, rough hew them how we will?' Is it a purely 
physiological phenomenon, dependent as Child (1911, '12, '13, '14) 
believes on the rate of metabolism at different poles? Or does polarity 
persist in some material substance which is not moved by centrifugal 
force? Investigators are not inclined to close the door to scientific 
research by a hasty resort to 'entelechy,' and differences in the rate of 
metaboKsm or of any other physiological process at two poles, when not 
due to differences in the environment, must be associated with differ- 
ences in the material substances at those poles. Consequently it seems 
necessary to conclude that there is some material substance or relation 
of parts in these eggs which persists with relatively little change, in 
spite of the dislocations caused by centrifuging, and which is capable of 
bringing these substances back to their normal positions when centrifug- 
ing ceases, unless they have been isolated in the meantime by the inter- 
position of partition walls. 
What is this substance or relation of parts in which polarity persists? 
LilHe (1906) concludes that polarity is a property of the 'ground sub- 
stance' of the egg, this substance being 'a fluid which has no filar, 
reticular or alveolar structure' but yet is 'firmly organized' so that 
it is not affected by centrifuging. The substances which are dislocated 
by centrifugal force are mere 'inclusions' in this 'ground substance;' 
consequently eggs in which these inclusions are forced to occupy abnor- 
mal positions are still capable of normal development since their 'ground 
