Hyatt.] 46 [March 5 , 



cipation of one of the points advanced in the following paper, 

 " auch besteht der Samen aller Thiere aus Infusorien." 



This author directly compares his cystic or Intestinal animals, 

 Infusoria, with ova and speaks of them as Oozoa, and in the pre- 

 face to the English edition of his Physiophilosophy, Lond. 1847, 

 Ray Society, he writes that " all organic beings originate from 

 and consist of vesicles or cells.' , Their production is noth- 

 ing else than a regular agglomeration of Infusoria ; not of course 

 of species previously elaborated or perfect, but of mucous vesicles 

 or points in general which first form themselves by their union 

 or combination into particular species." Oken's view was based 

 on observations of the resemblances existing between the Pro- 

 tozoa and the cells in the tissues of the Metazoa, and it is evident 

 he is entitled to be considered the first teacher of the unicellu- 

 lar doctrine, an honor now universally given to Von Siebold. 



Oken's effort to demonstrate the cellular structure of animals 

 and plants preceded the and more accurate work of Schleiden 

 and Schwann in 1838, and he appears, also, to have been the 

 first to recognize fully the essential ideutity in histological com- 

 position and structure of all forms of life. 



Von Siebold in his Anatomy of the Invertebrata, 1845, sepa- 

 rated the Protozoa from all the higher animals, and accurately 

 defined them as minute forms with slight undifferentiated struct- 

 ures, which were reducible to the ty^)e of a single cell. Prof. H. 

 J. Clark took the next step when he produced definite proofs, 

 that the sponges, though multicellular, were transitional forms 

 between the unicellular and multicellular animals, in his essay, 

 Memoirs of the Boston Society of Natural History, vol. i. 

 Before his time the proofs had been in continuation of the line 

 of general observation begun by Oken, and rested upon such 

 comparisons as could be made between the isolated cells of the 

 tissues, and the adult, unicellular zoons 1 of the Protozoa. 



1 We use the word Zoon to replace that of individual or person, and as a parallel 

 term with phyton as used among plants. Individual is an old term with an accepted 

 signification, meaning an organic being which cannot be divided, and, therefore, 

 must be considered as a whole. Person is equally objectionable since it means an in- 

 dividual having a certain character. The personality of God and of man are appropriate 

 expressions, but to speak of the personality of a polyp or a bion conveys no ideas 

 except erroneous ones. Zoon, in the sense here used, means any animal form contain- 

 'ng the elements of typical structures of the group to which it belongs. Thus a Pro- 



