METAMORPHOSIS OF AMPHIBIAN ORGANS 275 



Much more definite in time is the breaking up of the inner 

 section of the yellow ring into black and yellow dots, as it never 

 occurs before the Tigrinum host has left the water, a relation 

 which is in perfect accord with the attitude of the large majority 

 of normal punctatum eyes. And again, the more delayed the 

 host's going on land, the later the breaking up of the ring oc- 

 curred. In experiment 5, the eye, unfortunately was not watched 

 when the host left the water, but one month later when the 

 eye was examined for the first time, it showed the ring broken 

 up into black and yellow dots. Even if we assume this to be 

 the date of actual breaking up, this eye would have undergone 

 the change of its yellow ring almost one month earlier than the 

 eye of experiment 4, whose host correspondingly left the water 

 two months later than the host of experiment 5. 



Experiment VI . 

 Experiment VII 

 Experiment IV . 



HOST SET ON LAND- 

 CONDITION 



September 23, 1916 

 September 29, 1916 

 October 27, 1916 



BREAKING UP OF THE YELLOW 

 RING OF THE GRAFTED EYE 



September 30, 1916 

 October 4, 1916 

 October 31, 1916 



In experiment 4, the host and the graft were still in larval 

 condition when the hosts and grafts of the other 4 experi- 

 ments had metamorphosed. Since in this case the Punctatum 

 graft metamorphosed far later than any A. punctatum larva in 

 the experiments reported here, this experiment had particular 

 interest. On October 10, experiment 4 was pictured (Fig. 15), 

 and for comparison experiment 7 was pictured (Fig. 16). 



Figure 15 shows the host in a perfectly larval condition, the 

 gills and the fin of the tail still being very large. The grafted 

 eye, which can also be seen in the picture still possesses a bright 

 yellow ring in place of the iris; no black pigment can be detected. 

 In figure 16, which is a painted photograph of experiment VII, 

 the host is seen to be metamorphosed and has developed the 

 pattern of the metamorphosed young A. tigrinum. The graft 

 also is metamorphosed, as is demonstrated by its dark almost 

 black background color and by the lemon yellow spots which 

 it developed. The grafted eye appears very different from experi- 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 24, NO. 2 



