OBSERVATIONS ON FKESH-WATEK I'OLYZOA. 



143 



tinted from the re.st by assuming a spindle-sliape. These cells gradual- 

 ly separate from their mother-layer and form two loose bundles 

 which join the cœnœcium with the middle portions of the now two- 

 chambered bud. The parieto-vaginal muscles also originate in a 

 similar way, but at a considerably later stage, when the lophopliore 

 already shows a certain number of knob-like tentacles at its median 

 portion. Thus, in the process of budding, both the funiculus and 

 tlie muscles are de\ eloped as ditferentiations of the lining epithelium. 

 The young polypide. as it first evaginates, is a very pretty little 

 animal with less than thirty tentacles. The more medianly situated 

 tentacles are best developed, while they are yet knob-like nearer the 

 tip of the Icjpliophoral arms, where new tentacles are being added by 

 degrees. 



The buds arise ou the marginal cœnœcial branch alone, on the side 

 facing away from the centre of the colony, i.e., on the oral side when 

 we take the [)olypide into consideration. I'hey always develope in 

 pairs, one on each side of the median plane. Hence the dichotomy 

 of the cœnœcium, with a polypide-beariiig branchlet at each axil. 

 The colony as a whole is consequently fan-shaped at first. With 

 continued budding, it grows toward the periphery, its radius leng- 

 thening in arithmetical, and the marginal line in geometrical ratio. 

 The two extremities of the latter soon touch each other in a complete 

 circle ; after this the growth of the colony throws its marginal line as 

 well as its hitherto fiatly expanded surface into folds, which make 

 the regular arrangement of polypides unrecognizable at a glance. 



The upper series of diagrams in fig. 62. 1*1. XX, show early 

 stages in the development of a colony, each circle indicating an 

 individual. These figures represent for sake of simplicity each in- 

 dividual as giving off only two buds at a time, and each of these buds 

 again performing gemmation after some time. In reality, however, 



