LARVAE OF ARBACIA PUNCTULATA 



367 



cultures; all the averages were now so nearly equal that no con- 

 clusive evidence could be drawn as to the relative heights of the 

 various growth-curves at this particular period (figs. 55 to 60). 

 At the age of 48 hours, however, a was decidedly larger than 

 b and c (figs. 61 to 63) and an increased difference was evident 



Fig. 55 6a, 36 hrs. Control. Figure 56 66, figures 57 and 58 6c, figures 59 

 and 60 6d, 36 hrs. All of approximately the size. Variation increased and 

 asymmetry gradually acquired in the stronger solutions. 



Fig. 61 6a, 48 hrs. Control. 



Fig. 62 66, figure 63 6c, 48 hrs. Greater inhibition of growth in the alkaline 

 solutions. Retarded fusion of the various elements. Irregularity. 



