PREFACE. 



THE first principles of the present work I laid down in my small 

 pamphlet entitled Grundriss der Naturphilosophie, der Theorie 

 der Sinne und der darauf gegrundeten Classification der Thiere; 

 Frankfurt bey Eichenberg, 1802, 8vo (out of print). I still abide 

 by the position there taken, namely, that the Animal Classes are 

 virtually nothing else than a representation of the sense-organs, 

 and that they must be arranged in accordance with them. Thus, 

 strictly speaking, there are only 5 Animal Classes : Dermatozoa, 

 or the Invertebrata ; Glossozoa, or the Fishes, as being those animals 

 in whom a true tongue makes for the first time its appearance ; 

 Rkinozoa, or the Reptiles, wherein the nose opens for the first time 

 into the mouth and inhales air ; Otozoa, or the Birds, in which the 

 ear for the first time opens externally; Ophthalmozoa, or the 

 Thricozoa, in whom all the organs of sense are present and complete, 

 the eyes being moveable and covered with two palpebrse or lids. 

 But since all vegetative systems are subordinated to the tegument or 

 general sense of feeling, the Dermatozoa divide into just as many 

 or corresponding divisions, which, on account of the quantity of 

 their contents, may be for the sake of convenience also termed 

 classes. Thereby 9 classes of the inferior animals originate, but 

 which, when taken together, have only the worth or value of a 

 single class. So much by way of explaining the apparent want of 

 uniformity in the system. 



I first advanced the doctrine, that all organic beings originate 

 from and consist of vesicles or cells, in my book upon Generation. 

 (Die Zevgvng. Frankfurt beyWesche, 1805, 8vo.) These vesicles, 

 when singly detached and regarded in their original process of produc- 

 tion, are the infusorial mass, or the protoplasma (Ur-Schleim) from 

 whence all larger organisms fashion themselves or are evolved. 

 Their production is therefore nothing else than a regular agglo- 

 meration of Infusoria ; not of course of species already elaborated or 

 perfect, but of mucous vesicles or points in general, which first 

 form themselves by their union or combination into particular 



