. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. REPRODUCTION OF LIMACINA RETROVERSA 295 it seems better to speak of sex predominance and ratio between male and female predominance. The decrease in the value of this ratio from small to large-sized animals may be due, in general, to any one of the following causes : (a) Sexual dimorphism such that the males are habitu- ally smaller than the females, (fr) differential mortality, that is, more males than females die as the animals grow, and (c) sex reversal or an actual change in the condition of the reproductive system as th
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. REPRODUCTION OF LIMACINA RETROVERSA 295 it seems better to speak of sex predominance and ratio between male and female predominance. The decrease in the value of this ratio from small to large-sized animals may be due, in general, to any one of the following causes : (a) Sexual dimorphism such that the males are habitu- ally smaller than the females, (fr) differential mortality, that is, more males than females die as the animals grow, and (c) sex reversal or an actual change in the condition of the reproductive system as the animals grow. There is no evidence from our material either to show that there 100 80-. OEC JAN MAR APR MAY JUN SEP I 1 = NO DEFINITE SIGN OF FUNCTION 222 = FUNCTIONAL MALE |B * MATURE FEMALE E23 - FUNCTIONAL HERMAPHRODITE FIG. 8. Monthly distribution of the three functional types of Limacina retroversa. is a sexual dimorphism or to indicate a differential mortality which may be interpreted as the cause of the appearance of a higher proportion of males among smaller-sized Limacina and a greater number of females among larger ones. The third alternative, that a change in the pre- dominant sexuality takes place as the animals grow, however, has much evidence in its favor. In the first place, it has been shown above that there is a parallelism between the changes in the ratio of sex predomi- nance with reference to size and that with reference to the advance of the season: male types dominate among smaller-sized Limacina and dur-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-1983. Woods
Size: 1466px × 1705px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
