- 23 — 



the coelom also take part in building up the mid-gut. 

 On the ventral side of the abdomen we also find the 

 genital cells lying inside the ccelom, as will be described 

 further on. 



3. The Lateral Organ. — The lateral organ is 

 still to be found, but it seems to me to have ceased .to have 

 any function. Superficially it seems to be in the same 

 state as it was in the fourth stage; it is only on cuts 

 that the difference is remarked. 



Sections show that the lumen of the lateral organ is 

 no longer directly connected with that of the rest of 

 the body, and with the base of the fourth extremity in 

 particular. 



The cells which at a less mature stage formed the 

 walls of the lateral organ have died off, and it is only 

 here and there that traces of them are found. With the 

 drying up of the wall cells their plasma has been withdrawn 

 from the interior of the wart-like processes of the cuticle. 



In the fourth stage the outer cavity of the lateral 

 organ was filled with very small yolk particles; these 

 have now conglomerated and form a solid mass, staining 

 deep red with eosine. The partition that had begun to 

 form between the base of the lateral organ and the base 

 of the fourth extremity is now complete. 



A remarkable fact is that a substance resembling the 

 filling of the lateral organ is to be found in the adjacent 

 parts of the base of the fourth extremity. 



The shreds of dark substance covering the lateral 

 organ in the fourth stage have become much thicker (they 

 have been removed in the drawing (fig. la), so as not 

 to hide the lateral organ). This makes it appear more 

 probable that they have been secreted by the lateral 

 organ. 



4. The Coxal £rland. — At this stage the coxal 

 gland is at the height of its development. Only the gland 

 belonging to the third extremity is still to be found. It 

 occupies all the space between the cerebral ganglia and 

 the ventral ganglion -cord that is not occupied by the 

 muscle-stomach. Bulging over the sides of the ventral 



