THE PRODUCTIOX OF GRAFTED 



8 9 



The axes of the archenteron in the different gastrulaa of a 

 cluster were found in every possible angle with respect to one 

 another, suggesting that the polarity of the egg was unaffected 

 by the proximity of the other. Two gastrulae with their oral 

 ends together, and their archentera in the same axis are shown 

 in Fig. 59, and similar gastrulse with their archentera almost 

 in the same axis are shown in Fig. 60. The apex or aboral end 



of one gastrula may be attached to the side of the other and their 

 archentera about 90 apart as in Figs. 61 and 64, or almost parallel 

 in Fig. 62. The two gastrulae may be attached at or near their 

 aboral ends, Fig. 63. In Fig. 65 the oral end of one gastrula is 

 attached to the aboral end of the second, and the archentera lie 

 in an almost continuous line. In Fig. 66 the archentera lie in 

 the same axis, but the gastrulae are attached by their aboral ends. 

 Many other examples could be cited. They clearly point to the 

 conclusion that at this stage of development the polarity of the 

 gastrulae need not be changed by the proximity of other. 



FUSED GASTRULAE. 



The same conclusion obtains with reference to fused gastruhe. 

 In Fig. 67, the blastopores are at opposite ends, namely 180 

 apart and the archentera have grown toward each other in the 

 same axis. In Fig. 68, the blastopores are about 45 de grees apart 

 and the archentera have crossed each other at this angle. Per- 

 haps these two instances suffice as examples of this kind of inde- 

 pendent development of the archentera. In other instances 

 however the archentera met and fused. 



