MORPHOLOGY AND DEVELOPMENT OF EUDENDRIUM. 35 



Pigment granules are present in all parts of the entoderm. 

 They are most abundant in the gland ring. They are reddish- 

 brown in living tissue and greenish-yellow and non-staining in 

 alcoholic and formalin material. Lendenfeld, '83, found pig- 

 ment in the entoderm of the hydranth of Eitcopella cainpannlaria 

 and along the radial canals and about the egg of the medusa. 

 Since it occurs in regions of greatest metabolism he concludes 

 that it is the result of metabolism and therefore an excretory 

 product. A similar point of view is taken by Hargitt, '04, in an 

 extended consideration of the problem of coloring among Ccelen- 

 terata. In E. Jiargitti there is an association between the pigment 

 and gland cells. It is most abundant in the gland ring where 

 secretion is most active. It is found at the interior end of the 

 cells like other secretory products. I found a few cells in the 

 act of discharging it. Since it is as far as possible from the 

 exterior, its position is plainly least suited for producing a color- 

 ing of the animal. Small amounts also occur in the pedicels and 

 branchlets where the perisarc may preclude any color being seen 

 from the exterior. Since the habits of the animal do not point 

 to any advantage from its coloration I am inclined to think that 

 the pigment has chiefly, if not entirely, its reason for existence 

 in the metabolism of the animal. Between the gland cells the 

 entoderm contains shorter, less deeply staining columnar cells. 

 They become more abundant toward the base of the hydranth. 

 Gland cells exceed the others on the folds of entoderm resulting 

 from contraction of the hydranth. 



Fibrous muscle processes from the bases of the ectoderm and 

 entoderm cells, similar to those found by Kleinenberg in Hydra, 

 occur here. They stain readily in iron hcematoxylin and are so 

 abundant as to offer an unusually good opportunity for study. 

 They extend longitudinally along the mesoglcea in the ectoderm. 

 In favorable sections single fibers may be traced the entire length 

 of the hypostome. They are most abundant in the entoderm 

 where they take a circular course. In a contracted hypostome 

 they form a thick zone next the mesoglcea. Here it is easy to 

 see that the fibrous process of the cell consists of a thin sheath 

 of protoplasm surrounding a deeply staining filament. Longitu- 

 dinal ectoderm and circular entoderm fibers occur to less numbers 

 in all parts of the hydranth body and in the tentacles. 



