ARTIFIOIAL PRODUCTION OF NORMAL LAaRvVe 577 
several parts, which, however, were still connected.” These 
histological examinations were not thorough enough, and it 
was my intention to have them continued. The explana- 
tion I gave for this phenomenon was as follows: “The 
segmentation of the protoplasm is the effect of a stimulus 
which the nucleus applies to the protoplasm and which 
makes the protoplasm close around the nucleus.” On the 
other hand, if we put an egg into sea-water whose concentra- 
tion has been raised by the addition of certain salts, the 
protoplasm loses water, and this loss of water brings about 
a loss of irritability. There is a certain concentration at 
which the nucleus is still able to divide, while the protoplasm 
loses its ability to respond to the stimuli emanating from 
the nuclei. This, it seemed to me, was what happened in 
the more concentrated sea-water. The nucleus divided, but 
the protoplasm had lost its irritability on account of the loss 
of water. Hence there existed a segmentation of the nucleus 
without a segmentation of the protoplasm. But as soon as 
such an egg was put back into normal sea-water the proto- 
plasm began to take up more water and respond to the 
stimuli of the nucleus (these stimuli I considered to be 
chemical). Hence the protoplasm divided at once into as 
many cells as there were nuclei preformed.’ 
The following year Morgan stated that he had repeated 
my experiments and confirmed them, but was unable to 
agree with me as regards the nuclear division.” He found 
only one nucleus in the egg and concluded that no segmenta- 
tion of the nucleus occurs in the concentrated sea-water, but 
that a rapid division of the nucleus occurs when the eggs 
are put back into normal sea-water. As he had made only 
four experiments in ail, I asked the late Professor Norman, 
who worked in my laboratory, to make a larger number of 
1 Logs, Journal of Morphology, Vol. VII (1892), p. 253. 
27, H. MorGan, Anatomischer Anzeiger, Vol. IX (1894), p. 141. 
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