750 PROCEEDINGS OF THE ACADEMY OF [Oct., 



body was deeply stained by hsematoxyliiie. It arises near the pos- 

 terior end of the gland body, extends through the length of the latter, 

 then piercing the diaphragm extends forward through the archicoel 

 of the proboscis, i.e., on the surface of the axial stalk. Whether this 

 extremely delicate canal is intercellular or intracellular in the gland 

 body, I could not ascertain; if it were intercellular it would represent 

 a portion of the gastrocoelic cavity. As to the function of this gland, 

 the position of its external aperture at the base of the stilets would 

 point to its being a poison gland. There is no good reason for judging 

 it to be an excretory organ; and indeed we shall see that what are 

 probably excretory masses become stored up within the cavity of the 

 intestine. 



The intestine {In., fig. 36) of the larva is a closed tube, terminating 

 blindly at its anterior end, and at its posterior connecting with the 

 cuticula of the body wall without external opening; this latter point 

 corresponds with the blastopore {Bl.). This posterior end of the in- 

 testine appears as a narrow, solid stalk, with two or four nuclei apposed 

 to its surface. The wall of the remainder of the intestine is very thin, 

 except at the opposite ends where it is thickened and embraces several 

 large nuclei. Within the intestinal lumen are always present usually 

 two, sometimes more, large globules {Glo.) of a pale brownish color 

 and viscid consistency. These appear first when the larva is not quite 

 mature as a thinner fluid, but subsequently accumulate as homo- 

 geneous, rounded globules. These cannot represent food substance, 

 for the blastopore is closed and the intestine has no connection with 

 the exterior. It is then probable they represent products of metabolic 

 waste, in which case the intestine of the larva would serve as an excre- 

 tory reservoir. 



Within the archicoel, just at the posterior end of the head-trunk, is a 

 mass of a few small cells {Mus.), evidently mesenchym cells that have 

 not become specialized; they are embryonic, and may be germ cells. 



Finally, the body-cavity of the larva is an archicoel, without floating 

 cells and apparently without connective tissue. There are no meso- 

 dermal epithelia (mesothelia) ; and the only transverse septum of 

 the body, the diaphragm, is ectodcrmic. 



3. Previous Work. 



I have not seen the papers of Grube (1849) and Meissner (1856), nor 

 yet the last paper on the early development, one in Russian by Tretia- 

 kow (1901). 



Leidy (1850, 1870) gives a very superficial account, with no figures, 



