LARVAE OF ARBACIA PUNCTULATA 



361 



In very weak solutions, however, this does not involve a reduc- 

 tion in the number or size of the spine-like processes of the 

 arms; but in higher concentration of acid the latter effect also is 

 produced (fig. 42, oc). Correlated with the disappearance of 

 these spines, there is a retarded fusion of the separate rods in 



T Y„ 



riim^^ 



38 



3 9 



Figs. 33 to 48. Experiment 5. HCl. 

 Fig. 33 oa, 24 hrs. Control. 



Fig. 34 5b, figure 35 5c, figure 36 od, figure 37 oe, 24 hrs. Diminution of size 

 and irregularity of structure. 



Fig. 38 5/, 24 hrs. Blastula stage, somewhat irregular. 



Fig. 39 og, 24 hrs. Egg cytolyzed. Pigment collected in irregular clumps. 



Fig. 40 5a, 72 hrs. Control. 



Fig. 41 56, 72 hrs. All the parts more slender. 



