Germ-Colls in Chrysomelid Beetles. 233 



of embryology, but the great number of recent papers dealing with 

 the subject makes it advisable to give the following descriptions 

 which attempt to present, in a brief manner, the numerous frag- 

 mentary sketches of the various authors. 



1. Lepidoptera. 



The earliest worker whose results are worthy of consideration is 

 Herold (1815). He has given a remarkably good description of the 

 gross aspects of both ovaries and testes in several species of Lepi- 

 doptera, principally Papilio hrassica, from a late embryonic period 

 to the adult stage. For us the chief value of his results lies in his 

 discovery that the sex of the larva is already determined before 

 hatching. He foiuid the ovary to consist of four tubules, and the 

 testis of four small sacs; the former with a duct at its posterior 

 end and the latter with a duct extending from the center of its 

 side. 



In Bombyx pint, according to Heymons (1891), Suckow (1828), 

 disting-uished the male from the female before the larva hatched, 

 thus confirming Ilerold's results. This author described the rudiment 

 of the germ-glands as an outgrowth from the hind-intestine "das sich 

 spaterhin durch eine Furche theilt und nach und nach vom Darm- 

 kanale abgestossen als zwei seitlich verlaufende hohle Fadchen die 

 Geschlechtsorgane im ersten Entwnrf darstellt." 



The reproductive organs could not be found by Meyer (1849) 

 in Liparis auriflua until the caterpillars were over three weeks old, 

 and he wrongly pronounced the young larvse sexless. He was the 

 first, however, to make finer histological examinations of the devel- 

 oping germ-glands. 



Bessels (1867) made a more accurate microscopical examination 

 of the embryonic germ-cells than did Meyer (1849), and, contrary 

 to the results of the latter, he found that "Die Anlage der Sexual- 

 driisen findet bei den Lepidopteren im Ei statt, und es wird bereits 

 hier die Verschiedenheit des Geschlechts vollkommen deutlich." In 

 a late embryonic stage of Zeuzera cesculi he found the rudimentary 

 fferm-fflands at either side in the eighth abdominal segment embedded 



