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1 910] The Egg of the Walking Stick 8 



A number of zoologists who have worked on the structure 

 of the eggs of the Phasmidae claim that a "shell membrane" 

 exists within the inner surface of the chorion. Miiller (13) writes, 

 "Die innere Flache der Schale wird von einer sehr diinnen hau- 

 tigen Lamella, dei- Schalenhant, liberkleidet, die sich nur in kurzen 

 Stiicken von der Schale selbst wegnehmen lasst." Leuckart (10) 

 agrees with Miiller that a "shell membrane" lines the inner 

 surface of the chorion. "Dazu kommt als Bekleidung der innern 

 Chorion-flache noch eine eigne diinne 'Schalenhaut,' die schon 

 \'on J. Miiller aufgefunden ist. also wahrscheinlich unter den 

 Phasmoden eine ziemlich allgemeine Verbreitung hat, obgleich 

 sie den iibrigen Insekteneiern abgeht." In the eggs of Diaphero- 

 mera femorata the so-called "shell membrane" is the innermost 

 layer of the chorion, which peels off in small fragments in the 

 eggs that are in the early stages of development, but in the later 

 stages, as Leuckart (10) has observed, "Bei Cyphocrania lasst 

 sich diese Haut ohne grosse Schwierigkeiten in continuo abheben 

 — bis auf die Narbe, an der dieselbe fest mit dem Chorion ver- 

 wachsen ist und ein weisses Aussehen hat." To Leuckart's 

 observation may be added, in the case of the eggs of Diaphero- 

 mera femorata, that a firm attachment also exists at the rim 

 between the so-called "shell membrane" and the next outer 

 layer of the chorion. 



A microscopical examination of the operculum from the 

 outer surface shows a resemblance to the framework of a dome, 

 which is shut off at the base by a slightly concave floor of chitin. 

 The framework consists of brownish, irregularly-flattened, chi- 

 tinous rods. All of these rods arise from an elliptical or oval 

 brownish rim of chitin (Fig. 3, hr) which is in continuation with 

 the similarly colored upper surface of the floor of the dome 

 (Fig. 4, e) . Some of the rods anastomose, enclosing a large, more 

 or less, central space at the top of the dome (Fig. 3, c) and a 

 varying number of irregular areas (Fig. 3, d) which are not con- 

 stant in number in the different opercula. Those rods which do 

 not extend to the top of the dome project free into the irregular 

 spaces (Fig. 3, p). 



Various authors have called attention, in different Phas- 

 midae, to the resemblance in the histological structure of the 

 egg capsule to the structure of certain plant tissue. Murray (14) 

 finds, "a most striking resemblance to a piece of honey comb" 

 in the structure of the egg capsule of Phyllium Scythe. Accord- 



