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History of the Germ Cells and early Embryology of 
certain Aphids. 
By 
Geo. W. Tannreuther. 
With plates 49—53, 
Contents. 
Introduction. 
Natural history. 
History of germ cells. 
1, Spermatogenesis. 
2. Ovogenesis. 
a) Parthenogenetic generation. 
b) Sexual generation. 
3. General conclusions. 
Early embryological development. 
1, General statement. 
2. Development of the ova of parthenogenetic and presexual 
generations. 
3. Development of the ova of the sexual generation. 
4, Comparison and correlation. 
Summary. 
Material and methods. 
Bibliography. 
Description and explanation of plates. 
