Feb., 1921] 



Larval Colonies of PectinateUa 



125 



The animals are, as one would expect, somewhat negative 

 to light, but it is difficult to get precise records of the moving 

 forms. One can be exact with the colonies as they affix them- 

 selves. When attaching to the side of a battery jar covered 

 with pasteboard which had a rectangular hole two inches by 

 one inch cut on the window side of the jar, out of thirty-six 

 larval colonies, thirty attached on the half of the jar away from 

 the window and six on the half of the jar toward the window. 



The colonies were distributed vertically in a definite way 

 also, eight only being in the lower three inches of the water 

 and the rest in the upper four inches, more than half of the 

 thirty-six colonies being located between one inch and three 

 inches below the surface of the water. 



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r-*». 



Fig. 3 



Fig. 4 



Fig. 5 



Figure 3. 

 Figure 4. 

 Figure 5. 



PectinateUa. Sketch of camera drawing of recently set colon}'. X 100. 

 Four-polyp colony starved; fully differentiated; yolk all gone. X 25. 

 Last polyp of a starved colony, was letting loose from wall. IMth.= 

 mouth. An. = anus. At. = point of attachment. X 100. 



When no light at all was admitted to the battery jar, out 

 of thirty-four colonies, twenty-three attached in the lower three 

 inches of water and eleven in the upper tw^o inches. 



These colonies are also quite sensitive to foul water. At 

 11:30 A. M., one day an adult colony, which nearly filled a 

 battery jar, was brought in. At 1 :30 the adult was removed. 

 The next morning the water in the jar was foul, one hundred 

 and fifty colonies were in the first inch, eight in each of the next 

 two inches and seven scattered in the lower four inches of 

 water. In spite of the crowding to the top the attachment 

 of the one hundred and fifty colonies was chiefly on the side 

 of the jar away from the window, so the need for oxygen did 

 not inhibit the customary light reaction. 



