No. 2.] STOLONIZATION IN AUTOLYTUS VARIANS. 315 



from previously injured specimens. PI. XIII, Fig. 19, repre- 

 sents the posterior part of such a specimen of Autolytus varians 

 with a chain of stolons attached to the 44th setigerous segment, 

 presenting the normal phenomena of stolonization. In this indi- 

 vidual, presumably after injury, a second series of embryonic 

 segments has made its appearance between segments 40 and 

 41, and consists of six well-marked segments, in every way 

 similar in structure to that of the embryonic region of a 

 normal chain of stolons. All the segments have advanced 

 sufficiently far in the course of development to indicate their 

 future condition, and there can without difficulty be marked 

 out a developing stolon (St. i), in which the segment from 

 which the head will be formed has already developed well- 

 marked parapodia. Segment 41 has also undergone changes, 

 and gives unmistakable evidence of a head formation, thus con- 

 verting the four segments of the parent stock (41-45) into part 

 of another stolon. Anterior to stolon I is a segment {r.e) 

 which is similar to and represents the embryonic segments of 

 an ordinary chain. Anterior to this is a segment {s.a.) which 

 is larger than the embryonic segment, and in addition shows 

 developing parapodia, thus demonstrating without a doubt that 

 it is being added to the parent stock. 



This figure gives additional evidence that the zone of embry- 

 onic segments contributes segments, not only posteriorly for 

 the formation of the stolon, but also anteriorly for the length- 

 ening of the parent stock. In this way I think the great 

 length of some of the parent stocks (a length which I have 

 not been able to find in slender specimens) may be explained, 

 and in consequence the process of stolon formation in this 

 species may be regarded as being confined to a range between 

 segments 18 to 38, the range in which I have noticed the for- 

 mation of the first stolon of the chain in young individuals, 

 and not limited to^ accidental occurrence between segments 18 

 and 51. 



Origin of the Chain. 



The first indication of the phenomena of stolonization 

 appears in a young individual from 8 to 10 mm. in length and 



