Grafting of Tubularia 329 



{A) The piece designated A (Fig. 2) consisted of the major 

 part of the distal component, with a short distal piece of the prox- 

 imal component grafted in the same direction, on its aboral end. 

 If the long and short piece (Fig. 2, A) act as one, we should expect 

 a new hydranth to form first at the oral end (Fig. 2, X) and later 

 at the aboral end (Fig. 2, T). If, however, the two components 

 retain their individuality this result would not follow, for the oral 

 end of the small component and the aboral end of the large com- 

 ponent have had a start of twenty-four hours. 



Forty-seven grafts were made, the results from these are given 

 below in the table. 



TABLE I A 



Hydranths at X first, later at T l8 



Hydranths at A'none, later at T 14 



Hydranths simultaneously at X and T 6 



Hydranths first at T, later at A' 6 



Hydranths at T, none at .Y 3 



Total number of grafts 47 



From this table it is evident that the oral end of the long piece 

 is the region that produces the greatest number of hydranths, and 

 that when they form at both X and T (Fig. 2) they usually develop 

 at the oral end of the long piece before they appear at the aboral 

 end of the small piece (Fig. 3). About one-half of the hydranths 

 forming at T came entirely from the small piece, but in the reverse 

 direction therefore they are aboral hydranths (Fig. 3). In the 

 remaining one-half both components took part, the proximal row 

 of tentacles appearing in the long piece, and the distal row in the 

 short piece (Fig. 4). A large number of the grafts (almost one- 

 third) developed neither hydranths nor stolons at T. Six devel- 

 oped new hydranths simultaneously at X and T. Of these, four 

 of the aboral hydranths were composed partly of one, partly of 

 the other component (Fig. 4), and two developed in the small 

 piece only (Fig. 5). Twenty per cent of the grafts continued 

 development at the line of union showing however the influence 

 of the second operation, for the hydranths instead of taking their 

 usual direction emerged from the cut end (Fig. 6). In those that 



