352 JOHNS HOPKINS UNIVERSITY MORPHOLOGICAL MONOGRAPHS. 



contiguous, however, with the brain, one situated at the right, the other 

 at the left of the mid-ventral point of the ganglion (Fig. 1, Plate L). As 

 the wall of the branchial chamber separates more and more from the 

 surface of the ganglion, those portions of this wall which are adja- 

 cent to the two areas of adhesion are gradually drawn out into two 

 tubes reaching from the ventral surface of the ganglion to the branchial 

 chamber (Fig. 3, Plate L). The adult condition is reached by the con- 

 siderable growth of these tubes, which become greatly coiled, and by 

 the flattening out into a hollow disk of the portion of each tube con- 

 tiguous with the brain. Figs. 4 to 6, Plate L, serial sections in a longi- 

 tudinal, vertical plane, and Figs. 8 to 11, Plate L, serial cross-sections, 

 show the adult condition. In the former series Fig. 4 is nearest the 

 middle line of the body. In the latter series Fig. 8 represents the more 

 posterior section. The structure of the cells lining the tubes and hollow 

 disks (Plate L, Fig. 7) does not surely indicate their function. They are 

 smaller than the cells of the brain, irregularly cubical in form, have well 

 defined nuclei surrounded by finely granular protoplasm which, under 

 very high magnification, shows minute vacuoles. These may or may 

 not indicate secretory activity. The homologous cells in Salpa africana- 

 maxima are almost surely glandular, so it is probable these cells in 

 Cyclosalpa pinnata are more or less functional in secretion. 



In close connection with the enlarged ends of the tubes just described 

 there are four masses of cells, two on each side (Plate L, Figs. 4 to 6 and 

 10 and 11). One of these two masses, the more anterior (Figs. 4 and 11, 

 6'), is composed of large cells with large nuclei, resembling closely the 

 large ganglion cells that lie in the brain, in the zone of origin of the 

 nerves (Fig. 1, ri). The more posterior mass, 6, is composed of small cells 

 with small nuclei, having the appearance of the ordinary cells of the 

 periphery of the brain. These masses of cells develop simultaneously 

 with the lateral tubes (Plate L, Figs. 1 and 3) as outgrowths of the 

 ventro-lateral areas of the brain. What present function they may 

 have I am unable to say. Their homologies will be discussed later. 



In the solitary form of Cyclosalpa pinnata the adult structures 

 resemble minutely those described in the preceding pages for the chain 

 form. (See Plate LI, Fig. 7.) The early stages of development, too, are 

 the same. I have not traced the development for other species. 



The structure of the subneural gland and the organs connected with 

 it, in both chain and solitary forms of Cyclosalpa Chamissonis, is the 

 same as in Cyclosalpa pinnata. In other species there is a certain 



