ENDOSTYLE. 



43 



the rest and forms the perigonadial coelom which Hes in the 

 outer wall of the atrium (Fig. 10). 



The club-shaped gland and endostyle. The club-shaped gland 



B 



C 



IG. 30. — A, B, C. — Three side views of the ventral end of a. myotome of a young Amphioxus, 

 showing the development of the genital rudiment and its projection into the cavity of 

 the preceding somite (from Korschelt and Heider, after Boveri). 



is developed as a transverse groove on the floor of the pharynx 

 and continued on to the right and left walls. It becomes con- 

 stricted off from the pharynx, and acquires an opening to the 

 exterior on the left side of the body just in front of the mouth. 

 Later on the right end of it acquires an opening into the pharynx. 

 The club-shaped gland is of unknown function and eventually 

 atrophies. It has been suggested 

 without any obvious justification 

 that it is the metamorphosed an- 

 terior gill of the right side. 



The endostyle is a ciliated tract 

 of columnar epithelium just an- 

 terior to the club-shaped gland 

 on the right side (Fig. 24). It 

 subsequently becomes bent on 

 itself in a V-shaped manner 

 (Fig. 25), and grows backwards 

 between the two rows of gill- 

 slits. It is at first, therefore,' on 

 the right side of the body, but 

 when the larva becomes sym- 



mpfnVpl if fitp<a iir> if« nnsifinn Fm. 31.— Transverse section through 



metrical, it tanes up its position j,^g genital rudiment of a young 



in flip, vpntrnl mirlrllp linp ^mp/iioiMs sliowing tlie separation 



in tne ventral miaoie ime. j,^ ^^^ perlgonadlal coelom from 



From the above account it is f ^S?^°^l^ei ; ^^rgot"' Tfohi 



clear that in the young larva ^^^^oS"'"' '"" ^"'" 



