Some experiments on the developing ear vesicle of the tadpole with relation to equilibration / by George L. Streeter.

  • Streeter, George Linius, 1873-1948.
Date:
1906
Catalogue details

Licence: In copyright

Credit: Some experiments on the developing ear vesicle of the tadpole with relation to equilibration / by George L. Streeter. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    and a momentary loss of equilibrium which can be elicited by excitement. Three months after operation: The specimens passed through a normal metamorphosis at the end of the third month. A photo- graph made of one of them a few days after the completion of the process is shown in the 'accompanying Fig. 5. As long as they continued as swimming tadpoles the slight lean- ing toward the operated side persisted and it was possible through excitement to cause a momentary disturbance in equilibrium, but the latter became gradually more difficult to demonstrate. As soon as they commenced to make use of their legs the character of the swimming changed; it then became a series of leg strokes instead of the sinuous flexions of the body and tail. After that it was no longer possible to detect the leaning toward the operated side; both when swimming and when at rest their behavior was to all appearance normal. When taken out of water they jumped normally and came to rest in a normal posture. When turned over on their backs they righted themselves promptly. The fact that the slight disturbance of equilibrium, which could be still detected in the tail-swimming tadpole, could no longer be seen in the leg-swimming frog, a change completed within four or five days, probably does not signify the cure of the condition, but rather that under the latter circumstances a slight defect is more difficult to recognize. The corollary of this would be that equili- brium in the swimming tadpole is a more delicately balanced mechanism than in the kicking and jumping frog. Removal of Both Ear Vesicles During the first three days after the operation the appearance and behavior of these specimens are the same as seen in the normal ones, and in those from which one ear vesicle was removed. The response to stimuli is perhaps a trifle less prompt, but otherwise they could not be distinguished one from the other. Fourth day after operation: It was seen that in one-sided oper- ations the specimens commenced about this time to make excur-