58 HISTORY. 



Polyzoon of a different sjiecies from the " Polype a Panache," and probably a Plmnatella. 

 He informs us that he obtained them in England in 1745, and that, after having preserved 

 them for many months in a dry state, they produced young polypes on being placed in water. 

 He naturally considered these statoblasts as eggs. 



In the ' Transactions of the Royal Academy of Sciences of Stockholm, for the year 1746, 

 is a memoir on fresh-water polypes, by Bseck.* In this memoir two kinds of Polyzoa are 

 described; one is the " Polype a Panache" of Trembley, whose figures he reproduces ; the 

 other is probably Alcyoiiella. 



In Baker's 'Employment for the Microscope,' published in 1753, 1 we have, under the 

 name of " The Bellflower Animal," the description of a Polyzoon which would seem to be 

 identical with the " Polype a Panache." Baker is an accurate observer and a faithful recorder 

 of what he has witnessed. The structure of his " Bellflower Animal " is described with much 

 fulness ; like Trembley, he has recognised a complete digestive canal, and has even gone 

 further than the celebrated historian of the ' Polypes d'Eau douce,' in detecting the termination 

 of the intestine. 



In 1754, Schaffer published a memoir on the fresh-water polypes of the neighbourhood 

 of Regensburg.;}: In this memoir he describes and figures, under the name of " Kammpolyp," 

 a Polyzoon composed of branched tubes, which extend themselves over the surface of sub- 

 merged stems and leaves. There would seem to be little doubt of Schaffer's animal being the 

 true Plumatella repens of succeeding authors. 



In 1755, Rijsel published the first volume of the Supplement to his ' Insecten-Belus- 

 tigungen.'§ We have here a history of the fresh-water Polyzoa which had come under his own 

 observation. Under the name of " der Federbusch-polyp," he describes the Plumatella 

 repens ,■ his specimens mostly belonged to the free variation of this Polyzoon, while Schaffer 

 seems to have had in view the attached form. In his account of the internal structure, though 

 he had the advantage of Trembley 's and Baker's observations on the " Polype a Panache," he 

 falls far behind these naturalists in accuracy. He observed the statoblasts in the interior of 

 the tubes, and, under the impression that he had recognised similar bodies on the under 

 surface of the floating fronds of Lemna, he believes them to be the seeds of thisplant, and 

 supposes what he had seen in the interior of the tube to be some of these seeds which the 

 Polyzoon had swallowed. This belief had so taken possession of him, that, plainly seeing the 

 statoblasts external to what Trembley had already described as the alimentary canal, he is 

 forced to deny the accuracy of Trembley's account of the oesophagus, stomach, and intestine 

 of the " Polype a Panache ;" and though he has seen, and expressed in his figures the 

 expulsion of the faecal matter, and even, though imperfectly, represented the alimentary canal, 

 he cannot bring himself to recognise in this tube its proper function. The faeces, moreover, 

 are incorrectly figured as escaping at the side of the plume, opposite to the rectum. His 



* B^CK, ' Berattelse cm Watten Polyperij i anledning af dem som arc fundne otnkring Stockholm.' 

 Acta Holm., vii. 



■\ Baker, 'Employment for the Microscope' London, 1753. 



J J. Chr. Schaffer, ' Die Armpolypen in deu siissen Wasser um Regensburg entdeckt und 

 beschrieben.' Regensburg, 1754. 



§ RosEL, ' lusecten-Belustigungen.' Niirnb., 1746 — 1761. 



