368 RUTH B. ROWLAND 
ectoderm was not infrequent. Microscopic examination of 
sections through edematous embryos showed the tissues of the 
body to be in various stages of degeneration. Pressure of the 
accumulated fluid often forced the intestine ventrally or to one 
side and the fibers of the muscle plates were separated by large 
vacuoles. The muscle fibers themselves also became vacuolated, 
and in extreme cases the whole region was reduced to a spongy 
mass of irregular fibers with scattered nuclei. 
Although the splanchnopleural mesoderm which gives rise to 
the glomeruli had been left intact during the operations, the 
question nevertheless arose as to whether normal conditions of 
development would obtain for these organs in the absence of 
other parts so closely allied with them. Sections made through 
the operated region in embryos killed four days and six days 
after double excision showed capillary tufts extending out into 
the much-dilated coelomic cavity (fig. 9, gl). The tubular 
region cannot, therefore, be considered to exert any influence in 
the nature of a formative stimulus on the development of the 
glomeruli, since these parts of the system arise quite inde- 
pendently. Furthermore, the presence of the glomeruli in these 
operated cases would tend to strengthen the view supported by 
McClure ('19) that the glomerular filtrate, given off directly 
into the coelomic cavity, collects here in excess, producing the 
typical edematous condition already described. These embryos 
also showed well-developed anterior and posterior funnels, 
extending laterally into the regions from which the tubules had 
been removed, and ending blindly there. Segmental ducts were 
present, in some cases the lumina being flattened dorso ven- 
trally, in other instances the cells of these tubules showing 
marked signs of atrophy. The condition of the funnels and 
segmental ducts after extirpation of the kidney will be dealt 
with more fully in connection with the question of unilateral 
removal. 
Efforts were made to bridge over the interval between the 
operations and the beginning of functional activity of the meso- 
nephros. The first means applied was that of pricking the body 
wall as soon as abnormal distention was evidenced. The larvae 
