PYROSOMA DEVELOPMENT OF THE PROLIFERATING STOLON. 485 



large cells are seen in it which can be recognised us young egg-cells. 

 The rudiment of the genital strand has, in its turn, become abstricted 

 Prom the genital rudiment (o, h) of the parent (<■/. ms, in individuals 

 // and ///). 



Fig. 253. — A chain of three individuals of Pyrosoma (after Seeliger). /, youngest, 

 proximal bud ; //. middle and ///, oldest, distal bud (nearly fully developed). 1), 

 point at which the cndostyle-process of the parent enters ; d, endostyle- or entoderm- 

 process ; dc, rudiment of the alimentary canal ; <hn. elongate cell-mass ; >\ rudiment 

 of tlh- atrial aperture; eb, elaeoblasf ; Ec, ectoderm of the parent; ec, ectoderm- 

 plate of the stolon-rudiment ; Es, endostyle of the parent ; es, endostyle ; fg, ciliated 

 pit ; :/. ganglion ; h, testis ; lid. intestine ; hz, heart ; i, rudiment of the branchial 

 aperture; hi, atrium ; ks, gill-clefts; //, internal longitudinal gill-bars; lm, lenti- 

 cular phosphorescenl organ ; m, stomach ; /«••>•, genital strand ; n, rudiment of the 

 nervous system; <<. ovary (egg-follicle with egg); oe, oesophagus; p, dotteil line 

 indicating the boundary of the peribranchial sacs ; /><■. pericardium; rz, languets ; 

 /. tentacle-rudiment ; u, duct connecting the enteric cavity of the second individual 

 with thai of the third. 



These two rudiments (those of the entoderm-process and the 

 genital strand) ran also he recognised in a transverse section through 

 •Wis region of the body of the parent (Fig. 255). We then also see 

 that the entoderm-process is still accompanied by isolated mesen- 

 chyme-cells (Fig. •-'•"> J, ms). At the two sides of the process especially, 

 mesenehyme-cells can be seen arranged in two strands (pis). The 



