Heredity and sex . united in synapsis, it has takenno part in the process, hence the reduced number ofchromosomes in the male is seven — the seventh isthe sex chromosome. Two divisions now follow each other in rapid succes-sion (Fig. 21, C, D). In the first division (C) eachchromosome divides — seven go to one pole and sevento the other pole. Two cells, the primary spermato-cytes, are produced. Without resting, another divi-sion takes place (D) in each of these two cells. It isthe second spermatocyte division. Each of the sixordinary chromosomes divides, but the large sex chro-mosome does not
Heredity and sex . united in synapsis, it has takenno part in the process, hence the reduced number ofchromosomes in the male is seven — the seventh isthe sex chromosome. Two divisions now follow each other in rapid succes-sion (Fig. 21, C, D). In the first division (C) eachchromosome divides — seven go to one pole and sevento the other pole. Two cells, the primary spermato-cytes, are produced. Without resting, another divi-sion takes place (D) in each of these two cells. It isthe second spermatocyte division. Each of the sixordinary chromosomes divides, but the large sex chro-mosome does not divide, and, lagging behind the others, 42 HEREDITY AND SEX as shown in the figure (D), it passes to one pole. Eachsecondary spermatocyte produces, therefore, two cells —one with six, the other with seven chromosomes. Thesecells become spermatozoa {EE), the ones with sevenchromosomes are the female-producing spermatozoa, theones with six chromosomes are the male-producing Prot&nor ^ ••V •;•• ^1. c • • • ii 0
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Keywords: ., boo, bookcentury1900, bookdecade1910, booksubjectsex, bookyear1913
