Unless otherwise stated ligures were drawn from living specimens. 



Fig. 1 Experiment S. W. 33. Medullary tube of embryo of Rana palustris 

 cultivated 27 hours on spider web in serum from R. Clamitans. Some cells have 

 moved out in sheets on the cover-slip; others are adapted to the web fibers. X 50. 



Fig. 2 Experiment S. W. 34. Medullary tube from same embryo, cultivated 

 28 hours in large hanging drop of same serum as in figure 1. Considerable dis- 

 integration of tissue, but isolated cells are rounded and exhibit no active move- 

 ments. X 50. 



Fig. 3 Experiment 8. W. 66. Medullary tube (and notochord) of palustris 

 embryo cultivated two days in Locke's solution. The drop spread, leaving tissue 

 in contact with cover. Detached cells are all on the glass. X 50. 



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