ON THE VARIATION IN THE POSITION OF THE 

 STOLON IN AUTOLYTUS. 



P. CALVIN MENSCH. 



IN the investigation of the variation in the position of the 

 region of stolonization in bud-forming syllidians, observations 

 were made upon four of the most abundant forms occurring 

 along the Atlantic coast. 



Three of these forms - - Autolytus cornutus, Autolytus vari- 

 ans, and Proceraea ornata--may be found in abundance at 

 Woods Holl in the summer months, during which time also 

 the phenomenon of budding is most active. The fourth, Pro- 

 ceraea tardigrada, occurs in almost equal abundance at Beau- 

 fort, N. C. Of these A. cornutus, P. ornata, and P. tardigrada 

 are solitary stolon-bearing, and invariably cast off the first 

 stolon before a tra.ce of a second stolon appears, while A. 

 varians belongs to the chain-forming variety and may bear as 

 many as eight stolons in various stages of development attached 

 to the adult individual or so-called parent stock. 



The greatest number of variations were observed in the 

 chain-bearing form A. varians. The range in the position of 

 the chain stolon in this species is from segment 19 to 58. 

 The largest percentage of individuals were found to bear the 

 chain on or between segments 30 and 38 ; a smaller percentage 

 on or between segments 39 and 48, and an equal number 

 between segments 25 and 29; fewer between segments 19 and 

 24, and a very few between segments 50 and 58. 



In 155 individuals examined the following results were tabu- 

 lated. (The upper numerals indicate the number of the segment 

 to which the chain of stolons is attached ; the lower, the number 

 of individuals.) 



A J Seg. 30 31 32 33 34 35 36 37 38 

 ) Incl. 16 519 4 - IO 5 1 4 '3 

 89 



