No. 3.] STUDY OF STENOSTOMA LEUCOPS O. SCHM. 297 



Sometimes when worms in which the bud is well developed 

 are put into corrosive sublimate or osmic acid, the bud separates 

 from the mother before the worm dies. 



Graff ('82, p. 260) says that the asexual reproduction of Ste- 

 nostoma leucops occurs in the same manner as that of Micro- 

 stoma lincare, but he has never seen more than eight in a chain. 

 On page 173 he says that the first sign of a bud in Microstoma 

 lineare is a circular ridge on the outside of the intestinal wall at 

 the point which marks off the anterior end of the new bud. 

 This ridge is formed by a folding out of the intestinal wall. A 

 septum is next formed, which runs from this ridge to the integ- 

 ument. 



While this septum is being formed, a circular furrow of the 

 integument is becoming deeper and proceeding toward the ridge 

 on the intestine. While this furrow is forming, a thickening of 

 the parenchyme cells is noticed just posterior to the furrow and 

 in the median line of the ventral side of the body. This mass 

 develops into the pharyngeal cells. At the same time a pit 

 appears in the ventral body wall. This pit deepens and projects 

 into this mass of cells until it touches the wall of the intestine. 

 At the same time a cell mass separates off from either side of 

 this pharyngeal cell mass. These two separated masses grow 

 forward and backward and form the brain and oesophageal com- 

 missure. 



The eyes are now developed. Next the pharynx breaks 

 through into the intestine, long before the spontaneous separa- 

 tion of the bud from the mother. 



Thus according to Graff's account the wall of the pharynx is 

 developed from the integument, the brain is developed from the 

 pharyngeal cell mass, and there is a connection between the 

 intestine and pharynx of the bud for some time before the bud 

 leaves the mother. 



Wagner ('89, p. 191) agrees with Graff in regard to the 

 number of buds, the forming of the septa and the circular 

 furrow of the integument, and also in regard to the formation 

 of the ridge on the intestinal wall. He says also that the 

 brain of Microstoma lineare is first of the new internal organs 

 to develop, and that this is formed, not from the pharyngeal 

 cells, but from the lateral nerves of the body. Immedi- 

 ately behind the septum each nerve puts out a fibre mass 



