462 PATTEN AND HAZEN. [Vol. XVI. 



lobes, while the nephric lobes themselves were entirely over- 

 looked. They were further misled by not knowing the exist- 

 ence of the adult duct with its permanent external opening, 

 and other characters, which clearly distinguish it from the 

 nephric lobes, 



Kingsley ('93) supposed that the four nephridial lobes of one- 

 half of the body arose from a portion of the coelom of the 

 fifth somite, which had retained its position on the ventral side 

 of the embryo after the other coelomic cavities had emigrated 

 toward the dorsal surface. The fate of the dorsal portion of the 

 fifth somite was not determined, but he states that it persists 

 as a perfectly distinct cavity with epithelial walls on either side 

 of the heart. From its position and from its posterior termina- 

 tion he is inclined to think that this portion of the coelomic 

 epithelium is finally converted into the reproductive organs 

 (p. 200). "For a considerable time," he says, the ventral portion 

 of this coelomic cavity "shows no change worthy of remark." 

 At length, however, it "begins to elongate and to become bent 

 upon itself like the letter U, the rounded portion being directed 

 anteriorly." An ingrowth of ectoderm unites with this tube to 

 form its outer opening, situated on the posterior side of the 

 coxa of the fifth leg. He also states that "in the neighborhood 

 of the coxal gland at this stage may be seen numerous lacunae 

 in the mesoderm, which is rapidly assuming the trabecular con- 

 dition characteristic of the later stages " (p. 203). He was 

 unable to trace any connection between these lacunae and the 

 coelomic cavity, and is strongly of the opinion that none exists. 

 Again he states (p. 204) that there is a " formation of trabeculae 

 of mesodermal tissue which invade the cavity, and, passing from 

 wall to wall of the proximal portion of the organ, tend to sub- 

 divide it and give it an anastomosing character." In the older 

 stage he finds a fenestration in the region of the end sac, which 

 is "the beginning of the anastomosing condition of the adult, 

 while the proximal (internal) limb is thrown into a series of four 

 outwardly directed diverticula, which are segmentally arranged 

 and occupy somites 2-5 " (p. 205). Kingsley suggested "that 

 the whole organ of the adult is derived from the coelom of 

 somite V, and that the apparently metameric lobes figured by 



