104 PEOF. ALI/MAN ON a?HE 



lie takes tlie same view of the origin of these vessels in Beroe, 

 this does not correspond with the result of my own observations, 

 from which I felt justified in concluding that in JBeroe the two 

 vessels in question originate in a direct transformation of two of 

 the four sac-like masses which are differentiated out of the cells 

 of the endoderm. 



The larva increases in size ; the stomach, tapers from the wide 

 mouth towards the laterally compressed funnel into which it 

 opens. .From the funnel the vessels are seen to be given off ; 

 and their regular dichotomous distribution, which is so charac- 

 teristic of the Ctenophora, has begun to show itself. The four 

 prominences which had raised themselves round the central 

 nervous system have disappeared; and this lies henceforth free 

 on the summit of the aboral pole. 



The next development-stage o£ Eucharis is characterized by 

 the appearance of the lobes, and by the unequal growth in length 

 of the meridional vessels. The lobes show themselves as two 

 lateral projections lying iu the funnel-plane. At the same time 

 a difference in the length of the meridional vessels becomes 

 manifest, the four " subventral " vessels exceeding in length the 

 four " subtentacular." 



All the meridional vessels now grow rapidly towards the mouth- 

 margin, extending themselves along the outer side of the lobes. 

 When arrived at the oi^al region of the body, they begin to bend 

 round on each side towards one another, and the subtentacular 

 vessels anastomose with the subventral. The difference in length 

 between the stomach-axis and the funnel -axis has now almost 

 entirely disappeared, and the compressed Mertensia-like form of 

 the larva has given place to a nearly spherical form. 



To this stage of development would seem to succeed a re- 

 markable form, which, though Chun did not trace it by continuous 

 observation directly from the Eiicharis-lavYa, having only obtained 

 it in the towing-net, he believes, nevertheless, to be one of the 

 forms which enter into the post-embryonal metamorphosis of 

 Eucharis. The distribution of the vessels corresponds to that of 

 the stage just described; but it is the only Ctenophore in which 

 the main axis, or that which passes from the oral to the aboral 

 pole, is much exceeded in length by the two lateral axes. This, 

 along with the considerable development of the lobes, gives it a 

 medusa-like aspect. Now, too, for the first time in the develop- 

 ment-cycle of Eucliaris do we find the plane of compression of 



