North American Anura

North American Anura

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1914 edition. Excerpt: ... p. m., June 15, 1907: The table is to be read somewhat as follows: At the first sexual period there were three distinct fertilizations and three emissions, a fertilization and an emission being simultaneous. Between the first fertilization and emission and the second one there was an interval of 10 seconds, as there was between the second and the third. When the third was completed, the pair rested for 2 minutes. The egg-laying might last an hour or more. The female would become restless just before each sexual period. The fertilization took place beneath the surface of the water, when the female's body was at an acute angle to the surface and the dorsum of her head was above the water. After each fertilization the female would raise her vent above the water and lay 18 to 25 eggs. There would be three or four slight movements of the hind legs with each emission. In certain instances, after egg-laying had been completed, the pair remained in the embrace several hours. THE EGGS. In the field (Plate 1, Fig. 21) the first eggs found were secured May 27, 1906. Around a Potamogeton plant were three isolated patches of eggs numbering 6, 10, 14 respectively. Shortly after, they became cormnon among the tall grasses and plants in the marshes, in mid-pond, or in the open around the edges of the ponds. They float and may often be seen at a distance of several feet because of the excessive number of air-bubbles interspersed with each small bunch of eggs. During 1906 and 1907 eight different females laid in the laboratory. An estimate of one egg-complement (after a count of 400) was 1,800 to 2,000 eggs. A conservative estimate could not put the normal number below 1,000. The egg-packets (4 to 25) may be 6 to 12 inches apart, or only an inch or...
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Product details

  • Paperback | 46 pages
  • 189 x 246 x 3mm | 100g
  • United States
  • English
  • black & white illustrations
  • 1236857992
  • 9781236857996