Abstract
In my study of the development of the behavior of Amblystoma it became imperative to know whether or not eggs or embryos that had been subjected to a low temperature, in order to prolong the experimental season by retarding growth, followed the normal order of development of movements. To meet this requirement I conducted experiments in 1930. Regarding behavior the results were conclusively in the negative, but it seemed desirable to vary the conditions in further experiments before publishing the results, especially in consideration of the numerous and extreme structural defects that appeared in the experimental animals. But inasmuch as I have not been able, and probably shall not be, to repeat the experiments the most obvious results are here presented on account of their bearing on experimental morphology. The work was done in the biological laboratory of the Effingham B. Morris Biological Farm of the Wistar Institute of Anatomy and Biology. The special advantages of this laboratory are gratefully acknowledged.
Embryos from 2 clutches of eggs, designated 30M and 30E, were used for the experiments. They were collected from Gould's mill-pond in the Pocono Mts., Pa, April 13 and removed from the egg-masses, but not from the individual envelopes, on April 14. On April 20 they were placed in a mechanical refrigerator, the clutches in separate finger-bowls, where they remained till May 27. On this date the refrigerator was found not to be operating and defrosted, although it was operating on the previous day. The period of chilling was, therefore, 36 days. The temperature of the interior of the refrigerator fluctuated considerably with that of the room, which was also subject to rather marked changes according to the weather.
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