TRIPLE EMBRYOS. 285 



which one is A , the other occupying the position of B. The right hand embryo 

 then divides again, forming embryos B. and C. Thus two new generations of 

 halves are produced, // and ///, each consisting of an embryo with inverted 



FIG. 190. Diagrams illustrating the mode of growth of double and triple embryos. 



A. Diagram of a dividing limulus embryo showing the sequence in which the organs, a-e, of the two new halves 

 are generated. The newly formed, unpaired organs are in capitals; the organs formed by their division are in corre- 

 sponding small letters. The old halves shaded, new halves unshaded; see also explanation of Fig. 187. 



B. Diagram of a triple embryo. First generation of metameres, black and shaded; second, blank; third, 

 dotted. 



right and left sides. The three generations now form a tri-radiate figure, with 

 the new and old halves making three apparently normal embryos, A. B. and C. 

 But the halves of the original embryo are now separated by an angle of about 



