254 THE STRUCTURE AND AFFINITIES OF HERDMANIA CLAVIFORMIS. 



pearance of the granules. A little later clear spots appear in the nuclei, their sub- 

 stance stains less distinctly, they become more and more vacuolated or alveolar, until 

 finally they disappear entirely. I believe that they too are absorbed. 



IV. BUDDING. 



Although I have searched carefully through a large quantity of material for 

 young buds, I have not thus far been able to get more than a fragmentary view of the 

 process of bud reproduction. Half -grown blastozooids are of not infrequent occurrence, 

 and a considerable number of only partially differentiated ones have been found 

 first and last. Just where and how the bud arises, however, I have not determined. 

 I have not yet found any buds still connected with the stolonic partition, and it is 

 likely that they become completely severed from this normally at an early time as 

 they do in Distaplia and Amaroucium. My studies on this point have, however, 

 all been made on preserved specimens; and the stolonic partition is certainly given 

 to breaking up considerably on preservation. I am consequently still much in the 

 dark as to the exact relation of the zooids to one another. Most of the partly grown 

 zooids that I have thus far seen appear to spring from the posterior third of the older 

 zooids rather than from the stolon (Fig. 1), and on the whole I am inclined to believe 

 that it will be found that the buds originate not far behind the heart, so that in reality 

 the proliferating stolon is the portion of the zooid behind the heart, which may be 

 of considerable length. In the older parts of the colony, however, where the zooids 

 are all fully grown, there usually appears to be a large, much-branched, creeping 

 stolon. But this might be produced by the settling down upon the substratum of 

 the united body parts behind the point of origin of the buds as the colony extends 

 and becomes older. However, only further study on living colonies can settle the 

 several interesting questions relating to the asexual reproduction of the species. For 

 example, the question whether the two epicardia produce buds each for itself, or 

 whether both contribute to the same bud, is of much interest. As stated above, 

 the heart takes its origin from the larger right tube in the embryo. This makes it 

 highly probable that this tube is concerned in bud production. Does it give rise to 

 all the internal organs of the bud as does the primitive inner vesicle, derived from 

 the single tube, in other stolonic ascidians? If so, then what is the use of the left 

 tube? The answer to these' queries will be of great interest. 



