. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. LEECH GROWTH AND REPRODUCTION 329 (Mann, 1962), thus minimizing the distance that the sperm released from the implanted spermatophore have to migrate to reach the eggs. Gravid leeches could be recognized some weeks before they laid eggs, by a whitish clitellum that appeared in the ventral region surrounding the gonopores. Closer to the time of egg-laying, a large yellow area, showing yolky eggs in the ovisacs, could be seen on the ventral midline posterior to the gonopores. About 2 weeks before leeches laid eggs, the ventral
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. LEECH GROWTH AND REPRODUCTION 329 (Mann, 1962), thus minimizing the distance that the sperm released from the implanted spermatophore have to migrate to reach the eggs. Gravid leeches could be recognized some weeks before they laid eggs, by a whitish clitellum that appeared in the ventral region surrounding the gonopores. Closer to the time of egg-laying, a large yellow area, showing yolky eggs in the ovisacs, could be seen on the ventral midline posterior to the gonopores. About 2 weeks before leeches laid eggs, the ventral inflection of the lateral margins of the body gradually increased. This inflection eventually produced a brood pouch that protected the eggs in their cocoons attached to the venter of the parent (Fig. 5). To ensure fertilization of their eggs under the conditions of laboratory culture, gravid individuals were placed in a separate container with a consort of about 6 active sperm-donor individuals. The cocoons were normally deposited in pairs, one on each side of the ventral midline. When the number of cocoons formed was uneven, one unpaired cocoon usually took a medial position at the front. Figure 6, the results of a study of the fecundity of 125 H. ghilianii individuals, shows that the number of eggs per in- dividual per laying increased with body weight, from about 100 for the smallest leeches with mature female reproductive systems (10 g) to about 350 for the largest leeches (50 g). (One exceptionally large, 80 g leech laid nearly 500 eggs.) Table II also shows that the number of eggs laid increased with body weight. In contrast, the number of cocoons per individual showed no significant relation to body weight; the number varied between 6 and 12, with a typical value of 10. Thus, the increase with maternal weight in egg number per individual was accompanied by an increase in mean number of eggs per cocoon per individual, from a low of about 10 for the 10 g individuals to a
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
