120 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



As several authors have shown, the likelihood of the regeneration of a 

 given portion is decreased proportionally to the distance of the regenerat- 

 ing region from the part whose reproduction is expected. For example, 

 the head segments in the earthworm are much more likely to be regen- 

 erated from anterior segments than from middle or posterior ones. In 

 this case, too, the behavior suggests, one might say, a diminution of 

 head-producing material posteriorly. 



In addition to this normally recurrent relation between these two 

 regenerative processes in Dero, I have found in tw^o cases that, if a large 

 number of posterior segments are removed from a worm in which the 

 budding zone has just begun, the process of Inidding continues, without 

 any effort being made to regenerate the lost tail piece. In such cases, 

 however, the budding departs from the normal course, since the prolifer- 

 ations in what should become the head of the posterior zooid are amor- 

 phous, none of the normal structures being produced ; but the anterior 

 half of the budding segment produces an indifferent zone and an anal 

 segment in the customary w^ay, with, however, minor imperfections. 

 Here the behavior is as if the regenerative process had been transferred, 

 as a matter of economy, to the budding region instead of taking place 

 where the injury existed. In a case where only a small number of seg- 

 ments were removed, the cut being immediately in front of the indiffer- 

 ent preanal zone, regeneration occurred at the point of cutting, and the 

 ectodermal thickening of the budding zone disappeared. After the re- 

 generation of the tail piece was completed, the animal formed again the 

 budding zone in the original segment (in this instance the 18th setige- 

 rous) and ultimately divided. 



It is a suggestive fi\ct, that, furthermore, in the sexual individuals, 

 some of which are known to be asexually produced, I have found that 

 the testes are formed upon the posterior face of dissepiment iii/iv, i. e. 

 on a new dissepiment produced in the process of budding, in a region 

 which was of course located in the parent individual much posterior to 

 the usual place of production of gonads. The ovaries arise likewise 

 upon the posterior wall of the dissepiment between setigerous segments 

 iv/v. Although this is one of the original dissepiments, the new tissues 

 are closely related to it in their origin and development. 



5. Experiments on the Rate of Budding. 



In the effort to secure an abundance of budding material, there ap- 

 peared certain facts of practical and perhaps theoretical importance 



