550 ADAM SEDGWICK. 



in the region where they are detached from the pericardial floor. Zeiss's F, 

 oc. 2. 



Fig. 49.— Longitudinal vertical section through the anterior part of the 

 body of an embryo of Stage f. Reduced ^. 



Fig. 50. — One side of a transverse section through a young embryo of Stage 

 r. To show the latest stage of the rudimentary nephridium of the first somite 

 (s. 0. 1), in close contact with the outer side of the hind part of the brain (a 

 few nuclei of the latter are indicated). Zeiss's D, oc. 2. Reduced i. 



Fig. 51. — One side of a transverse section through the brain of a late em- 

 bryo of Stage F. To show the two separate parts of the first somite. The 

 cerebral grooves are closed. Reduced |. 



Fig. 52.— Transverse section of the sixth leg of an old embryo of Stage F. 

 To show the funnel-shaped opening (/.) of the tubular portion of the nephridium 

 into the vesicular internal portion (1. s. v.), and the relation of the latter to the 

 body cavity (pseudocoele) of the leg {d. app.). Zeiss's D, oc. 2. Reduced |. 



Fig. 53, a and b. Longitudinal horizontal sections of two contiguous legs 

 of an embryo of same stage as last. Reduced ^. 



