ON 151OL0GICAL ANALOG IKS. 



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the Animal Nature of Diatomeae," which comes to this at last — 

 ;; 1 conclude, however, that in the actual state of science, the 

 Diatomese are to be enumerated among animals, but at the same 

 time much remains to be accomplished in order to disclose their 

 intimate organization and vital phenomena." 



Haeckel proposes, in his " History of Creation " (ii., 48) to place 

 eight of the simplest groups of living creatures in a separate 

 kingdom intermediate between the animal and vegetable, under the 

 name of Protista. These are Monera, the Amccboidea, the 

 Flagellata, the Catallacta, the Labyrinthulece, the Diatomece, the 

 Myxomycetes, and the Rliizopoda. This is a poor method of 

 getting out of a difficulty, and one which I think will only be 

 accepted as a temporary and provisional expedient. Afterwards he 

 hints at Monera as merely a simpler form of Amcebce, and the 

 latter of Rhizojyoda, so that through the last named they are linked 

 to the animal kingdom. The affinities of the Myxomycetes are un- 

 doubtedly with Gasteromycetous Fungi, and the Diatomece with 

 conjugating Algaa. Hence the bulk of Protista find their relation- 

 ships in the vegetable and animal kingdoms respectively. 

 Because no logical definition, which is indisputable, has been found 

 to mark the limits between the two kingdoms, is no reason for 

 cutting the " inextricable knot " so rashly. Time and patience may 

 reveal the affinities of all the " doubtful beings " which he has 

 determined to " exclude from the animal as well as from the 

 vegetable kingdom, and to comprise them in a third organic 

 kingdom standing midway between the two others." Or perhaps 

 this may be an obscure way of hinting that organic life is the same 

 whether in plant or animal, and that all were linked by the Protista 

 in one homogeneous whole, which ultimately divided into two 

 branches having their origin in one trunk. At least his view 

 strengthens the position assumed in this Address. 



Ehrenberg included amongst his Polygastric Infusoria the 

 Closterina, Bacillaria, and Volvocina ; that is to say the Desmi- 

 diacece, the Diatomaceos, and the Volvocina?. Siebold found it 

 necessary to combat this arrangement little more than thirty years 

 ago. # Amongst other suggestions he says that " we can scarcely 

 expect chemistry to decide what is animal and what plant, having 

 several times been deceived in our hopes in this respect. The non- 



* Siebold and Kolliker, " Leitschr. fur Wiss. Zool.," I, p. 270. " Qnart. 

 Journ. Micr. Sci.," Ibi53, pp. 111-159. 



