Heredity and sex . Fio. 2. — Conjugation in Paramcxjcium. The niicronucleus in one indi-vidual is represented in Ijlack, in the other by cross-lines. The macro-nucleus in both is stippled. A-C, division of micronucleus into 2 and4 nuclei; C^-D, elongation of conjugation nuclei, which interchange andrecombine in E; F-J, consecutive stage in one ex-conjugant to show threedivisions of new micronucleus to produce eight micronuclei {J). In lowerpart of diagram th(! first two divisions of the ex-conjugant (/) with eightmicroriufhi arc shown, Ijy means of which a redistribution of the eightiiiicronuc
Heredity and sex . Fio. 2. — Conjugation in Paramcxjcium. The niicronucleus in one indi-vidual is represented in Ijlack, in the other by cross-lines. The macro-nucleus in both is stippled. A-C, division of micronucleus into 2 and4 nuclei; C^-D, elongation of conjugation nuclei, which interchange andrecombine in E; F-J, consecutive stage in one ex-conjugant to show threedivisions of new micronucleus to produce eight micronuclei {J). In lowerpart of diagram th(! first two divisions of the ex-conjugant (/) with eightmicroriufhi arc shown, Ijy means of which a redistribution of the eightiiiicronucl(;i takes place. See also P^ig. 100. THE EVOLUTION OF SEX E 1. E Fig. 3. — The nuclei of two individuals of paramoecium in I (homozygousin certain factors, and heterozygous in other factors), are represented as di^-id-ing twice (in II and III); the first division, II, is represented as reducing, segregation occurs ; the second division. III, is represented as equational, no reduction but division of factors, as in the next or conjugation division,IV, also. 8 HEREDITY AND SEX Maupas found by following from generation togeneration the division of some of these protozoa thatthe division rate slowly declines and finally comes toan end. He found that if a debilitated individualconjugates with a wild individual, the death of the raceis prevented, but Maupas did not claim that throughconjugation the division rate was restored. On thecontrary he found it is lower for a time. He also discovered that conjugation between tworelated individuals of these weakened strains producedno beneficial results. Blitschlihad earlier (1876) suggested
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Keywords: ., boo, bookcentury1900, bookdecade1910, booksubjectsex, bookyear1913
