94 NATURAL HISTORY. 



by some observers, by which all the stony zoophytes were 

 regarded as being mineral productions, and therefore 

 really of an inorganic nature. Ray, for example, unhesi- 

 tatingly grouped the zoophytes generally among the sea- 

 weeds and mosses, though he seems to have thought 

 that some of the harder sorts ( ' Lithophytes ' ) were per- 

 haps really inorganic. An occasional naturalist, even 

 before the close of the seventeenth century, seems to have 

 ventured to express doubts as to the truth of the prevalent 

 doctrine regarding the vegetable or mineral nature of 

 zoophytes, but the first clear assertion of the animal 

 nature of these organisms was made by Peyssonnel, in a 

 memoir which he laid before the Paris Academy of 

 Sciences in 1727, but which does not seem to have been 

 published. The views of Peyssonnel did not meet with 

 acceptance; and it was not till 1741, when the experi- 

 ments of Trembley * upon the fresh-water polypes brought 

 the subject again under the notice of the scientific world, 

 that the question was once more seriously discussed. 

 Incited by Trembley's experiments, Bernard de Jussieu 

 investigated the nature of various marine zoophytes care- 

 fully, and presented a memoir to the French Academy 

 of Sciences in 1742, in which he maintained the animality 

 of these organisms. The views of Jussieu were accepted 



* Abraham Trembley was born at Geneva in 1710, and died in 1784. He is 

 best known through his work dealing with the structure and life-history of the 

 Hydra or fresh-water polype ( ' Memoires pour servir a 1'histoire d'un Genre de 

 Polypes d'eau douce, a bras en forme de comes,' 2 vols., Paris, 1744). Leuwenhoek 

 had given some account of the Hydra, and of its propagating itself by means of 

 buds, as early as 1703 ; but Trembley first investigated the entire subject of the 

 habits, generation, and power of resisting mutilation of this interesting animal. 

 His experiments were repeated by many naturalists, and an English observer, 

 Henry Baker, published an ' Essay on the Natural History of the Polype,' in which 

 he fully confirmed the chief discoveries which had been announced by the Swiss 

 naturalist. 



