Zool.— Vol. I.] TORREY—MONOGENESTS IN METRIDIUM. 353 



One case of this laceration was observed in a polyp in 

 its natural environment. All the others occurred in aquaria, 

 where the conditions were not so favorable. This unfavor- 

 able environment may have had some influence in initiating 

 this method of reproduction which was not begun by cer- 

 tain polyps until they had been in captivity for more than 

 six months, when fragments were thrown off, occasionally 

 three or four at a time. 



IV. Budding. 



Buds may occur either upon the upper surface of the 

 expanded foot disk or in the region of the oesophagus. In 

 the first case, the bud is always, relatively to the parent, 

 very small, and its oesophagus and siphonoglyph are formed 

 independently of the corresponding structures of the parent. 

 In the second, the bud may almost equal the parent in size ; 

 its oesophagus arises from the oesophagus of the parent; its 

 siphonoglyph may be independent of the siphonoglyph of 

 the parent from the beginning, or the siphonoglyph of the 

 parent may enter the bud, in which case the bud possesses 

 two instead of one. 



(a.) fecial — Budding from foot region. — Seven polyps 

 have been taken with these marginal buds. In one of these 

 cases the bud has broken away from the parent; in another 

 the process of division is advanced ; in the others it has not 

 yet begun, although the polyps have been under observa- 

 tion for several months. 



In the earliest stage seen, the bud was a small rounded 

 protuberance near the edge of the foot disk. In the course 

 of preparation for sectioning it was lost. All the other spec- 

 imens were in an advanced stage and bore tentacles when 

 collected. 



The rate of detachment is low, to judge from observations 

 taken in the laboratory, where the conditions are not favor- 

 able. The only bud which has become free in the labora- 

 tory aquaria was taken March 30th. On April 5th it was 

 seen to be detaching. The expansion of the foot disk on 



