File:Aquatic life (1920) (19739738582).jpg

Title: Aquatic life
Identifier: aquaticlife51920baus (find matches)
Year: 1920 (1920s)
Authors: Bausman, Joseph E
Subjects: Aquariums; Fish culture
Publisher: Philadelphia : J. E. Bausman
Contributing Library: Harvard University, Museum of Comparative Zoology, Ernst Mayr Library
Digitizing Sponsor: Harvard University, Museum of Comparative Zoology, Ernst Mayr Library

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I f.— An Interesting Abnormality LESLIE TA5CHE Zoological Laboratory), UniOersitj) of Wisconsin
Text Appearing After Image:
Yellow Perch, Perca flavesens. Showing Two Ani Photograph by A. S. Pearse Jh The abnormal has always been inter- esting. Normal structure, although in- teresting from a purely scientific stand- point, fails to attract the attention of the average man. It is too commonplace. The abnormal* on the contrary is made conspicuous by its noticeable dissimilar- ity to the normal. People since the be- ginning of time have preserved and ex- hibited every variety of unnatural forms. "Freaks of Nature," as they are called, and have wondered at their origin and development. During the early periods of civilization there was a great deal of superstition connected with many of these malformations. Many forms were feared and great reverence was extended to them, because they were thought to be the work of spirits, others were used as charms for luck and for medicinal pur- poses, but most of them were kept mere- ly because they were different. As civ- ilization advanced, most of these super- stitious views were discredited and men began to examine them scientifically as to origin and development; but to this day people of many classes still believe in the supernatural powers of some of the types and everybody is more or less in- terested in any striking malformation that is put on exhibition. Scientific in- vestigations have shown that these forms are the result of unnatural embryological development or the product of patho- logical changes in the growth of parts of the body in respect to size, shape, posi- tion, or number. An example of one of these "Freaks of Nature" is found in a yellow perch, Perca flavesens (Mitchill) : the presence of two ani situated exactly on the me- dian line. The fish was caught on No- vember 23, 1917, in Lake Mendota near Madison, Wisconsin. It was normal in size, measuring 16. i centimeters in length, and apparently in good condition. The presence of two ani came to the no- tice of Professor A. S. Pearse while he was preparing to dissect the fish in order to determine what it had eaten, and he took the accompanying photograph. The presence of two ani in the Class Pisces is not a very rare thing by any means, but such openings are usually paired; one to the right and one to the left of the median line, usually at right

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