ON BUDDING IN ANIMALS. 9 



It is in the lower Turbellarians, however, that linear budding 

 is conspicuous — for example, in Microstoma and Stenostoma — in 

 which a chain is formed behind the adult. So little is known of 

 the life-history of these forms that it is difficult to determine the 

 advantages of linear budding in contrast with the young produced 

 from eggs in the ordinary manner. 



Linear budding likewise occurs in the Oligochsetous division 

 of the bristled Annelids, as in Stylaria and Chcetogaster. In 

 Stylaria lacustris, 0. F. Miiller originally described two kinds of 

 budding, viz. (1) That in which the last segment sprouted into a 

 number of body-rings which ultimately constitute a new in- 

 dividual. This last segment gives origin to other buds, the 

 hindmost being the oldest, and the anterior the youngest, as 

 well as the smallest. After these buds have been thrown off the 

 segment next in front takes on a similar function, and is able to 

 reproduce buds. (2) When the body has attained the length of 

 forty segments, suddenly a division begins in the middle, so that 

 two bodies each of twenty segments are formed. Budding in the 

 same species was next alluded to by Gruithuisen* in his account 

 of its anatomy. Oscar Schmidt, t again, thought that the de- 

 velopment of the bud in Stylaria took place after the manner of 

 an embryo and its nurse. Max Schultze,t further, described a 

 softening of two body-rings which develop an opaque cellular 

 substance filling the segment symmetrically, and a new body- 

 segment forms, and so on until a number of body- and tail-rings, 

 as well as a head-segment anteriorly, are developed out of the 

 end-segment. Then a new bud is formed in front, and again 

 another, so that a series of three individuals, each with head, 

 eyes, proboscis, and body-segments, is present. These are now 

 detached, and the process is repeated. When, however, by 

 these means the body of the parent-stock has been reduced to 

 twelve or fourteen rings, a pause ensues. After forty or fifty 

 segments have been developed by increase at the posterior end 

 a new cycle commences, for the animal divides into two, as 

 0. F. Miiller described. The latter author thought that the 

 separation took place between two segments, but Max Schultze 



* ' Nova Acta Acad. Cass. Leop.' Bd. xi. 1, pp. 243-248, 1823. 

 f ' Handbnch der vergl. Anat.' p. 293. 

 | ' Archiv f. Naturges.' 1849, pp. 293-304. 



