A study of the chromosomes in meiosis, fertilization, and cleavage in the grasshopper egg (orthoptera)†

摘要: A technique is developed whereby the large heavily yolk-laden grasshopper egg may be sectioned for cytological study. Eggs of Chortophaga viridifasciata and Circotettix verruculatus were examined. In C. structure late ovarian nucleus chromosomes in meiosis, fertilization, early cleavage are described. In first maturation twelve rod-shaped tetrads found. Near caudal end a polar body given off, second division there dyads. At separated vesicles female pronucleus seen scattered about male which prophase. In chromosome numbers metaphase found to differentiate male- female-producing eggs. former twenty-three latter twenty-four chromosomes. vesicular condition retain their boundaries interkinesis indicative individuality. A comparison oocyte with those spermatocyte shows similar compact group on spindle, likeness size seriation, similarity form. They differ that complex eleven one dyad. This latter, unpaired sex chromosome, falls among chromosomes. A indicates constancy generic differences form, size, number, behavior