if d 





10 



Figs 8 to 11- Duodenum of nine-day chick embryo cultivated with different 

 kinds of solid support. Drawn from specimens preserved two days after explan- 

 tation. X 39. 



Fig. 8 In clotted plasma. 



Fig. 9 In serum in contact with cover glass. 



Fig. 10 In serum on spider web. 



Fig. 11 Free in large hanging drop of serum. „^„ t^ , .• ^t 



Yil 12" Portion of figure 10 under high power. X 300. Explanation of 

 details in text. 



23 These preparations, which were used to illustrate a general paper read 

 before the Imerican Congress of Physicians and Surgeons, have been redrawn 

 (except fig. 31) for the present account in order to show greater exactness of detail. 



537 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 17. NO. 4 



