Germ-Cells in Chrysonielid Beetles. 235 



not from a muscle fiber (Schneider, 1885). In late embryonic life 

 each o-erm-gland consisted of four large ''Urzellen der Geschlechtsan- 

 lagc" with small cells lying Ix'tween them, the Avhok' mass being s\iv- 

 roundetl by a tlat-cellcd ei)irli('lium. As the four ''Urzellen" increased 

 by mitosis, the surrounding sheath grew inward, thus establishing 

 the four testicular follicles. 



The earliest appearance of the primitive germ-glands of Lepi- 

 doptera was recorded by Woodworth (1889) in EiCvanessa antlopa. 

 About the time the blastoderm was completed, a group of cells became 

 cut off from the ventral plate near its posterior end ; these cells 

 remained ''in contact with the ventral plate at the place where they 

 are produced. Later stages show that these cells produce the genera- 

 tive organs. The generative organs thus appear to be produced by 

 an infolding of the ectoderm, or possibly of the blastoderm before 

 the ectoderm is produced but from a position which is later to become 

 ectoderm." 



In a nine and a half day embryo of Pieris craiwgi, Graber (1801) 

 figured the "Anlagen der Samendriisen" on either side of and dorsal 

 to the intestine, thus occupying a position similar to that found by 

 Selvatico (1882) in Bomhyx mori. Each ''Anlage" consisted of 

 a few large cells and was surrounded by a small celled epithelium, 

 the whole being embedded in fat-body. 



Silk worm embryos, having appendages well developed, were found 

 by Toyama (1002) to contain the rudiments of germ-glands. ''Al- 

 though the clusters of germ-cells are normally seen to occur in the 

 third and sixth abdominal segments, we oft^n observed them in all 

 other abdominal segments with the exception of the anal ; and in one 

 case, we observed them even in the mesothoracic segment. We are 

 thus in a position to say that the genital ce-lls originally arise in 

 each body segment." They differentiated from the cells of the 

 mesoblastic somites. 



The most recent account of the origin of the germ-cells in Lepi- 

 doptera was published by Schwangart (1905). He found in 

 Eiulrotnifi rersiroloin \]\c first indication of a germ-gland two to 

 four hours after blastoderm formation. A part of the blastoderm 

 in the posterior region of the egg, but not at the posterior end, became 



