212 Relation of Nervous System to the Developing Musculature 



5.29. Some of the palustris larvae react with a jerk or two. 

 545. All of the palustris larvae react to stimuli. Several able to swim 

 across the dish. 



Fig. 14. Embryo of R. palustris kept five days in a 0.03 per cent solution of acetone- 

 chloroform. X 9- 



Fig. 1.">. < oiitrol embryo kept five days in water, x 9. 



May 6. The recovered tadpoles have been kept in a large aquarium, with 

 plenty of food. The palustris larvae appear normally formed when seen 

 from above and from the side. One has remained very small. The intestinal 

 coils are not normal. Of the virescens larvae, two are normal looking, except 

 for the intestinal coils. One is very much swollen on the sides, due probably 

 to distention of the lymph sinuses. 



The histogenesis of the muscular tissue was followed in a series of 

 specimens, taken from the above and other experiments and preserved 

 from day to day. The embryos were iixed in mercuric chloride and 

 acetic acid and the sections stained for the most part in Heidenhain's 

 iron hematoxylin. 



Experiment 6. Palustris embryo two days in 0.03 per cent solution. — 

 The muscle cells in the myotomes are normal. They still contain a large 

 amount of yolk but no vacuoles. Contractile fibrillae are present in consider- 

 able quantity. 



Experiment H. Palustris embryo three days in 0.03 per cent solution. — 

 Corresponding with the general retardation of development as compared with 

 that of the control embryos reared in water, the development of the individual 

 muscle cells is retarded (cf. Fig. 16 and Fig. 17). There is more yolk* in the 

 muscle fibers of the drugged specimen; the striations of the muscle fibrillae 

 are in corresponding myotomes less distinctly marked. The individual fibers 

 are not so slender as in the normal control. When a comparison is made 

 between the less differentiated myotomes in the tail and those in the trunk 

 of the normal specimen, it is seen that the difference in the clearness of the 

 striations is merely an evidence of the difference in the degree of develop- 

 ment. There is a slight vacuolization of some of the muscle fibers in both 



