108 



EMBRYOLOGY 



septum (Fig. 52 E, st), is produced by their contiguous lateral 

 walls. These four septa He in the interradii, whereas the four 



Fig. 52.— Diagrammatic sections through various successive stages of ^invlia 

 (after Goette). .4, planula; ec, ectoderm ; en, entoderm ; B, attached larva with 

 forming ossopliageal invagination, .s ; g, mesogloea ; C, completed rupture of the 

 (esophageal invagination ; sji, inner opening of the oesophagus ; m, gastral pouches ; 

 D, transverse section through the stage represented in C at the level of the 

 oesophagus; E, transverse section through an older stage at the level of the 

 oesophagus ; F, transverse section through the same stage at a piirt nearer to the 

 stalk; s, oesophagus ; st, septa; t, tseniote. 



primary yastral pouches lie in the four chief radii (perradii). 



the proboscis in the developing Ephyra of the strobila stage, a point which 

 had not hitherto received any careful attention. 



Eecent observations by Goette (No. III.) on Cotylorhiza tuberculata 

 and Pehujid noctiliico have led to the astonishing result, that of the four 

 primary gastral pouches, — although the first pair is of entodernial origin, 

 being produced from diverticula of the archenteron, — the second pair is 

 ectodermal in origin, since it arises by evagination from the ectodermal 

 pharynx.— H.] Consult also Ida H. H\i>e, No. VII. i^.— Tkanslatohs. 



