318 



BULLETIN OF THE 



stages, while, during all stages but the earliest, it is hidden in the 

 chain-sal pa by the testis. The second -portion of the nucleus, which 

 is much larger than the portion which forms the digestive organs is 



Fig. 24. 



Embryo at the time the first traces of the stolon appear: 1, sinus system of rmrse ; b, outer 

 tunic of nurse; c, branchial tunic of nurse ; h, branchial cavity of nurse ; 6', outer tunic ; 

 d, atrial tunic ; e, branchial aperture ; /, muscles ; g, atrial aperture ; 7s', branchial cavity ; k 

 heart ; I, epipharyngeal ridges ; 7?!., endostyle ; o, mouth ; o', oesophagus ; o", stomach ; x, 

 elaeoblast. Through an error the ganglion, as well as the heart, is marked it. 



situated upon the hsemal side of the body, as already stated (see Fig. 

 23, x), and soon becomes divided up into large transparent cells, filled 

 with oil globules, or with a body of oil-like appearance and refractive 

 power, but not divided into globules. These cells soon become polyg- 

 onal by mutual pressure, and form a large spherical mass which in- 

 creases much more rapidly than the remaining organs of the body 

 (Fig. 24, x), and at the time the Salpa chain begins to be formed 

 within the body, the mass of cells is nearly as large as all the other 

 portions of the embryo. The blood circulates freely among the cells 

 and over the outside of the mass, which is not separated from the 

 sinus system by any membrane, and the blood globules, and the oil 

 which escapes from the older cells, often accumulate in large masses 

 near the digestive organs and heart. 



