362 



GRACE MEDES 



the anal arms (figs. 43 to 46, solutions d, e and /). Figure 45 

 from 5e, 72 hours, represents a typical specimen, nearly sym- 

 metrical, with arm- and body-rods forming a widely spread V. 

 There is no evidence of spines and the number of cross-bars in 

 the arms is greatly reduced. The ventral branches are lacking. 

 In contrast with the gradual disappearance of spines and 

 cross-bars, there is a tendency toward formation of accessory 



Fig. 42 5c, 72 hrs. Reduction in size. All the parts more slender. Spines 

 lacking from the arm -rods. 



Fig. 43 5d, 72 hrs. Slender and more reduced in size. Arm-rods unfused, 

 with accessory rods across the lateral connectives. Posterior body-rods promi- 

 nent. 



Fig. 44 oe, 72 hi-s. Same characters, more pronounced. 



Fig. 45 5e, 72 hrs. Body symmetrical, slender. Arm-rods slighth* fused, 

 spreading. 



Fig. 46 5/, 72 hrs. Same characters, still more marked. Greater reduction 

 in size. 



Fig. 47 5d, 96 hrs. Same characters, not so pronounced as in the stronger 

 solutions. Four rods in each arm. 



Fig. 48 5e, 96 hrs. Irregularity of structure. Accessory rods on oral arms 

 and at point of fusion of lateral connectives. 



