498 PATTEN AND HAZEN. 



throughout the tissue. A bunch of small, round cells, with fine granules around 

 their periphery (/-g-c), is seen, apparently within the large cell on the left, x 270. 



Fig. 51. Some of the hollow cells which nearly surround the nephridial lobe 

 {k.c, Fig. 49). It shows cells with a finely granular periphery, apparently uniting 

 end to end. X 270. 



Fig. 52. Enlarged section through the tubules lined with large granular cells. 

 X 270. 



Fig. 53. Enlarged section of the tubular part {t.p.) of the lobe. The tubules 

 are surrounded by a loose connective tissue, in which not infrequently were large, 

 round cells with granular protoplasm {c). The tubules form an anastomosing 

 network throughout the central portion of the lobe. They have a cellular lining 

 which is separated by a dark membrane from the connective tissue {cMs.). x 270. 



Fig. 54. Enlarged portion of the longitudinal collecting tubules {c.t.). The 

 tubules are large and branching. They have a heavily striated lining, which is 

 separated by a dark membrane from the connective tissue. Nerves and capillaries 

 are shown in the connective tissue, and also a few large granular cells, similar to 

 those in Fig. 53. x 270. 



Fig. 55. Cross-section through the anterior part of the fifth appendage of a 

 specimen the same age as that in PI. XXIV, Fig. 36 (5 fi, haematoxylin). The 

 section shows the nephric plate of mesoderm cells at the base of the appendage. 

 It is continuous on both the lateral and median sides with a cellular membrane 

 which lies upon the yolk, x 200. 



Fig. 56. The fourth section posterior to Fig. 55, showing an evagination of 

 the nephric plate to form the nephric duct, x 200. 



Fig. 57. The third section posterior to Fig. 56, showing the posterior margin 

 of the nephric plate, x 200. 



Fig. 58. Reconstructed outline of the nephridial duct and end sac, made from 

 a specimen of the same age as PI. Ill, Fig. 40. X 400. 



