110 EMBRYOLOGY 



dermal cord grows frorn the apex of each gasfcral pouch 

 diagonally upwards and outwards, pushing before it the 

 ectoderm of the outer margin of the peristome. The ento- 

 derm cells in the tentacular buds soon arrange themselves 

 in a single row (Fig. 53 0- 



Other important fundaments of organs are represented by 

 the septal funnels which are now established. Four funnel- 

 like invaginations arise from the ectoderm of the peristome in 

 the interradii ; these sink into the septa, and extend down- 

 wards as solid cords of cells, which are continued along the 

 teeniolae and even beyond these into the stalk (Fig. 53 B ; 

 Fig. 54 A and (7, tr). In this solid portion, the cells appear 

 to be fused with one another, and on their surface longi- 

 tudinal muscle fibrillge are differentiated, so that the four 

 [septal] longitudinal muscles extending in the taeniolse arise 

 in this way (Fig. 54 A, B, sm). 



The young Scyphistoma thus produced is characterized 

 therefore as a goblet-shaped polj^p, with four longitudinal 

 folds (teeniolse) of the entodermal sac extending upwards 

 as four septa, w^hich are stretched between the body- wall 

 and the invaginated ectodermal oesophagus. The stomach is 

 accordingly divided into a central cavity and four gastral 

 pouches (peripheral intestine \^Kranzdarm']\ which lie be- 

 tween the septa and are directly continuous with the gas- 

 tral furrows. Four perradial tentacles are attached to the 

 margin of the peristome, while four interradial septal fun- 

 nels extend from the peristome into the septa and taeniolsB 

 (Fig. 53). 



The metamorphosis into older Scyphistomse (Figs. 54 and 

 55) takes place by an increase in the number of the ten- 

 tacles and other changes, which efface more and more the 

 original characters, and lead by a gradual transition to the 

 structural plan of the Ephyra. 



The budding of the tentacles presents many irregularities. Heretofore 

 it has been believed that normally after the formation of the first four 

 tentacles, radial in position, the development of four interradial ones {i.e., 

 placed over the septa) took place, and then, after all these eight tentacles 

 had reached the same length, ensued the development of eight others, 

 lying between them (therefore adradial), and so on. According to Goette, 



