IIO RALPH S. LILLIE AND WARE CATTELL. 



Unfertilized eggs are thus insensitive to the current as compared 

 with most irritable or active cells of other kinds. 



3. When the eggs are exposed in a stream of running sea-water 

 to stronger currents (600-800 ma. /cm.) for brief periods (| to 2 

 minutes), definite effects are produced. The eggs undergo 

 marked deformation during the passage of the current, and a 

 variable proportion afterwards show fertilization-membranes and 

 partial activation. Complete activation of a large proportion of 

 eggs was not possible in our experiments, although a few de- 

 veloped to the blastula stage. 



4. We conclude that the unfertilized starfish egg is insensitive 

 to currents of moderate intensity, and exhibits activation only 

 when currents are used of such intensity as to produce definite and 

 well marked structural changes in the egg-system. 



5. Similar exposure of unfertilized sea-urchin eggs (Arbacia) to 

 strong currents, with and without after-treatment with hyper- 

 tonic sea-water, gave inconstant or negative results. 



