206 



BEHAV lOR OF ISOLATED CELLS 



/ HIGRATIOH 



ccr:; 



S ^<:^ 



c d 



MIGRATION AHO AOHESiON 



10 ATTRACTION WITHOUT ADHESION 



Q"& 



PHAOOCnoSIS 



Fig. 7. Migrating vermiform cells, Isolated from the medullary plate, failing to 

 aggregate. 



Fig. 8. Cells from the medullary plate becoming adhesive to each other while chang- 

 ing from a cylindrical into a spherical shape, the Intervals between each 

 picture being about 5 minutes. 



Fig. 9. Successive phases of kinetic relations between a sessile and a migrating 

 neuroblast. 



Fig. 10. Three ectoplasmic cell fragments exhibiting reciprocal attraction, but no 

 adhesion. 



Fig. 11. Ectodermal cells in tlie process of aggregating, tlie wliole process taking 

 about 20 minutes. 



Fig. 12. Aggregations comprlsln;^ various numbers of cells, some of whicli are at 

 the seune time spreading on glass. 



Fig. 13. Spreading embryonic cell containing 2 particles of carbon. 



Fig. 14. Cylindrical cell having Ingested a drop of paraffin oil. 



Fig. 15. Neuroblast attempting but failing to incorporate a droplet of paraffin oil. 



Fig. Ifi. Neuroblasts leaving an embryo wliicli lias been exposed to a hypertonic salt 

 solution. 



Holtfreter, 19l^7: Jour. Morphology. 80:57. 



