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H. H. NEWMAN. 



varying times of exposure to low temperatures were tried. Each 

 culture was divided evenly into two lots, one for control and one 

 for experiment. As all lots were allowed to develop for a week or 

 more before the census, the results may be readily tabulated as 

 though belonging to one census though it took about three days 

 to complete the count. 



TABLE I. 



SUMMARY OF TABLE I. 



(a) In Experiments 4, 5, 6, and 7, in which blastulae were used, the iced lots 

 showed a marked increase of symmetry reversal over the controls. Including those 

 showing bilaterality among the reversed types, there are over 27 per cent, on the 

 average, of reversed larvae, as compared with 12 per cent, for the controls. 



(6) In Experiments 8 and 9, where gastrulae were used, there was no significant 

 increase or decrease in the percentage of larvae with reversed asymmetry as the 

 result of low temperatures. This is in accord with Experiment 3, in which a large 

 proportion of the larvae were gastrulae and in which the increase in reversed larvae 

 was relatively slight. 



(c) Only in Experiments 6 and 7, where the larvae were exposed for long periods 

 to low temperatures (7 and 18 hours, respectively) were any larvae found with 

 water pores and pore canals on both sides. It might then be said that bilaterality is 

 harder to induce than reversal of asymmetry. 



