182 THE EMBRYOLOGY OF THE HONEY BEE 



ment of the oenocytes of the grasshopper Stenobothrus. Here 

 the oenocytes are derived by delamination from the inner surface 

 of the lateral ectoderm. In the beetles Hydrophilus, Melolontha 

 and Lina Graber finds presumptive evidence that the oenocytes 

 are derived from the ectoderm near the eight abdominal stigmata, 

 including special "metastigmatic" invaginations, one of which is 

 situated directly caudad to each of the eight abdominal stigmata. 18 

 In Hydrophilus and Melolontha these invaginations are situated 

 near the posterior border of the segments some distance behind 

 the spiracles, in Lina they are close behind them. 



Wheeler (1892) has reviewed the work of previous investiga- 

 tors and described briefly his observations on the development 

 of the oenocytes in the representatives of the Orthoptera, Ephe- 

 meridea, Hemiptera, Neuroptera and Lepidoptera. In all cases 

 they were found to arise by either delamination or migration from 

 the lateral ectoderm, and the metastigmatic invaginations of 

 Graber were found not only in representaives of the Coleoptera 

 but also in representatives of the Orthoptera (Blatta, Xiphidium), 

 but Wheeler believes that they play only a minor part in the pro- 

 duction of the oenocytes. 



Heymons (1895) studied the development of oenocytes in 

 Forficula and Gryllus. He states ''that by means of simple 

 migration or through the intervention of Graber's metastigmatic 

 invaginations they find their way into the interior of the 

 body and thence into the already formed fat body. Here for a 

 long time they form sharply marked, metamerically arranged 

 groups of cells. Later they become more irregularly distributed 

 throughout the abdomen, and also find their way into the thorax, 

 but are nevertheless to be here easily distinguished from the true 

 fat cells principally by their size." So far this corresponds 

 closely with Wheeler's account (1892) of Blatta and Xiphidium. 

 Heymons was, however, able to add the important fact that 

 oenocytes are developed from all of the eleven abdominal seg- 

 ments, and not merely from those bearing spiracles, as had been 

 previously assumed to be the case. Moreover these "postspiracu- 

 lar" oenocytes differ from the remainder by their larger size. 



18 Wheeler (1892) states that Patten (1889) had previously observed 

 these in Acilius. 



