THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL 



YoL. IIL 



New York, AuGrsT, 1882. 



No. 8. 



The Protista.* 



BY E. HACKEL. 



A good negative criterion to char- 

 acterize the protista as regards ani- 

 mals and vegetals, is that they pos- 

 sess neither a gastrula with its two 

 germinative layers, like the former, 

 nor a thallus or prothallium, like the 

 the second. It may be added that 

 the protista never have veritable tis- 

 sues (constituted by a large number 

 of associated cellules) nor organs, 

 like all animals and vegetals. Finally, 

 it is particularly necessary to note 

 that the great majority of all the pro- 

 tista are produced by asexual genera- 

 tion (scissiparity, budding, spores). 

 Even among the small number of pro- 

 tista which have already attained to 

 the most simple form of sexual gene- 

 ration, there never exists between the 

 male and female a distinction so 

 marked as among the animals and 

 the vegetals. In this regard they are 

 the representatives of the earliest de- 

 gree of inferior development which 

 existed prior to the evolution of 

 plants and animals. 

 / If we knew exactly how organic life 

 developed from its origin upon our 

 planet, how the animals, the protista 

 and the vegetals appeared for the 

 first time, we might form a clear 

 and ciTtain judgment upon the rela- 

 tions between the three realms. But 

 the path which conducts us to the 

 immediate knowledge of this great 

 problem is eternally closed to us. No 

 living creature, no document of crea- 

 tion, can relate to us how, millions 

 and millions of years ago, life devel- 



*Abstract, translated for this Journal from 

 the French. Joxir. de Phot, et de Micr. 



oped. Thousands of species and 

 genera, millions of generations, have 

 fallen into the abyss without having 

 left the slightest trace of their exist- 

 ence. And precisely the more im- 

 portant for us of all these creatures, 

 the forms most ancient and the most 

 elementary, have left no fossils, their 

 bodies being destitute of hard parts. 

 But, if we cannot, by the experi- 

 mental method, attain any knowledge 

 of this great question of origin, it is 

 permitted us here, as in other cases, 

 to fill the irremediable lacunes of our 

 science by scientific hypotheses. If 

 that " historical hypothesis " is found- 

 ed upon facts that science has hither- 

 to established, it is as firm, as justified 

 in natural history, as it would be in 

 geology, archaeology, in the history of 

 civilization, or in any other historical 

 science. And as the hypotheses 

 generally recognized have conducted 

 us to a satisfactory understanding of 

 the development of our globe, so the 

 phylogenetic hypotheses which are 

 based upon the theory of descent re- 

 formed by Darwin, explain the devel- 

 opment of organic life upon the earth. 

 We cannot dwell upon tlie examina- 

 tion and the proofs of all the divers 

 phylogentic hypotheses which have 

 been proposed to explain this develop- 

 ment. We will consider at least one 

 idea which to-day seems to have 

 great probability. One must admit 

 that life began upon this planet by the 

 spontaneous formation of the most 

 simple protista at the bottom of the 

 combinations of inorganic matter. 

 These living creatures, of antiquity so 

 great, must have resembled the 

 raoners which exist to-day, excecMl- 

 ingly simple masses of protoplasm 



