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On the Maturation Mitoses 

 and Fertilization of the Egg of Theridium. 



By 



Thomas H. Montgomery, Jr. 



With Plates 4-5. 



Herold in 1824, in his "De generatioue Aranearum in Ovo", 

 made not only the first contribution to the embryology of araneads, 

 but also one of the first comprehensive studies on invertebrate de- 

 velopment. Since his time much has been added to the embryologj^ 

 of spiders, nevertheless so far nothing has been made known con- 

 cerning the phenomena of the fertilization of the egg, save for the 

 following fragmentary observations. Menge (1871) supposed that 

 the eggs are fertilized during oviposition. Bertkau (1875b) reached 

 the same conclusion as Menge even though he was unable to find 

 spermatozoa in the clear fluid poured out at the time of egg la5ing ; 

 but in another paper (1875a) he suggested that impregnation of the 

 eggs was possible within the oviducts in certain species {Oletera, 

 Tetragnatha, Pachi/gnatha; Therididae and Attidae), a judgment based 

 on the structure of the receptacula seminis. Then Schimkewitsch 

 (1887) proved that fertilization occurs in the body, and that the 

 eggs are already impregnated when laid. Much more is known of 

 the maturation of the paternal germ cells from the investigations 

 of Wagner, myself, Wallace and Berry, though here there is con- 

 siderable confusion of results. 



Zool. Jahrb. XXV. Abt. f. Anat. 16 



