. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 644 P. ROE. FIGURE 1. a. Polar body formation in egg of control Carcinonemertes epialti. Chromosomes nearest edge of the cell are those of the polar body. Some cells showed 12, other cells showed 13 chromosomes during meiotic divisions. Magnification: 1500X. b. Chromosomes in mitotic anaphase during division from one to two cell stage in embryo of control Carcinonemertes errans. The small dark spots to the left of the chromosomes are remains of chromosomes in the two polar bodies. Magnification: 1000X. c. Chromo- somes in mi
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 644 P. ROE. FIGURE 1. a. Polar body formation in egg of control Carcinonemertes epialti. Chromosomes nearest edge of the cell are those of the polar body. Some cells showed 12, other cells showed 13 chromosomes during meiotic divisions. Magnification: 1500X. b. Chromosomes in mitotic anaphase during division from one to two cell stage in embryo of control Carcinonemertes errans. The small dark spots to the left of the chromosomes are remains of chromosomes in the two polar bodies. Magnification: 1000X. c. Chromo- somes in mitotic anaphase during division from two to four cell stage in haploid embryo of experimental Carcinonemertes errans. Chromosome number is one-half that of Figure 1 b. Magnification: 1000X. Con- trols are worms raised in groups. Experimental worms are worms raised in isolation. begin to feed until many days after the experiments started and therefore were very slow to develop. Some of these females never developed to the point of laying eggs. In addition, of the 440 egg strings of experimental animals observed either with a compound or stereomicroscope to determine if the eggs were dividing, at least 430 strings had dividing, developing eggs. Finally, after two experimental females had made egg strings with haploid embryos, males were added to their culture dishes. Of the eight egg strings checked for chromosome numbers that were made after males were introduced, two egg strings had haploid embryos and six had diploid embryos. DISCUSSION These studies show that females of Carcinonemertes can produce offspring by parthenogenesis when necessary. That larvae produced by isolated females are indeed produced by parthenogenesis is supported by several lines of evidence. The primary evidence is that these larvae are haploid. In addition, there is no question that these females are indeed females and not self-fertilizing hermaphrodites. Both in cultures and in nature one sees a 50:50 se
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
