EMBBYOLOGY OF CAMPANULARIA GELATINOSA. 



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but subsequently, at each angle there is developed another cell, con- 

 necting the two groups together, and making the whole number to 

 amount to twenty-four. These twenty-four cells will afterwards be- 

 come the tentacles of the polyp. 



Fig. 48. 



Embryology of Campanularia gelatinosa. A, an ovarian vesicle from which an embryo is in 

 the act of escaping ; others, in a less advanced state, are seen in the interior. B, a detached 

 embryo in a very early stage, showing the vitellus and blastoderm. C, another embryo, more 

 highly magnified : 6, cells formed around the vitellus. D, the same, more advanced : a, cavity 

 enclosing the remains of the vitellus ' 6, elongated cells subsequently developed into tentacula ; 

 c, other cells, eight in number, which are the rudiments of the organs of the senses. E, the same 

 in a more advanced condition. F, an embryo at the moment of its escape from the ovarian vesicle, 

 magnified : a, fleshy pedicle ; 6, mouth ; d, muscular fasciculus ; e, nervous ganglion ; ff t organs 

 of sense; g, tentacles. G-, the same, as it swims in the water, presenting all the characters of a 

 Medusa. 



(252.) Cells of another order now make their appearance (fig. 48, D, c), 

 grouped together in pairs, behind the preceding, with similar regularity. 

 These will become organs of sense. 



(253.) It is difficult to avoid making the comparison between the 

 above appearances and those of crystallization ; the cells, in fact, arrange 

 themselves precisely like crystals, with perfect symmetry, and always 

 in accordance with the number four or its multiple. 



(254.) The embryo, at this period of its development, presents the 

 shape of a thick lens-like disk ; and shortly, from the centre of its in- 



