Heredity and sex . lands. They beganvery soon to change into frogs, but ceased to grow insize. The tadpoles might begin their metamorphosisin a few da^^s after the fiist apphcation of the th\Toid,and weeks before the control annuals did so. In contrast to these effects Gudernatsch found thattadpoles fed on thymus grew rapidly and postponedmetamorphosis. They might even, in fact, fail tochange into frogs and remain permanently in the tad-pole condition. If thyroid extracts produce dwarfs;th^TQUs extracts make giant tadpoles that never becomeadults. These examples will suffice to show some of th
Heredity and sex . lands. They beganvery soon to change into frogs, but ceased to grow insize. The tadpoles might begin their metamorphosisin a few da^^s after the fiist apphcation of the th\Toid,and weeks before the control annuals did so. In contrast to these effects Gudernatsch found thattadpoles fed on thymus grew rapidly and postponedmetamorphosis. They might even, in fact, fail tochange into frogs and remain permanently in the tad-pole condition. If thyroid extracts produce dwarfs;th^TQUs extracts make giant tadpoles that never becomeadults. These examples will suffice to show some of the im-portant effects on gro^\i:h that these internal secretionsmay bring about. 148 HEREDITY AND SEX OPERATIONS ON INSECTS The Insects constitute the third great group in whichsecondary sexual characters are common. The first operations on the reproductive organs werecarried out by Oudemans on the gipsy moth, Ocneria(Porthetria) dispar. The male and female are strik-ingly different. Oudemans removed the testes from. Fig. 74. — Ovaries of Lymantria {Porthetria) dispar transplanted to have established connection with the sperm ducts. (After Kopec.) young caterpillars and found no change in the color, orsize, of the male. He also removed the ovaries fromyoung caterpillars, and again found no effect in the fe-male. The same experiments were later carried out ona large scale by Meisenheimer, who obtained similarresults. Meisenheimer went further, however, and per-formed another operation of great interest. He removedthe male glands from a male and implanted in their THE EFFECTS OF CASTRATION 149 place the ovary of a female, while it was still in a veryimmature condition. The caterpillar underwent itsusual growth, changed to a chrysalid, and then to amoth. The moth showed the characters of the presence of the ovary had produced no effect what-ever on the body character of the individual. Whenthis individual was dissected, Meisenheimer found thatthe ovary had comp
Size: 1754px × 1424px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., boo, bookcentury1900, bookdecade1910, booksubjectsex, bookyear1913
