oie 
* ve ANIMAL TISSUES. iF 
tissues proceed originally from homogeneous elements. Fonrana, 
and afterwards TREvIRANUS, busied themselves with this enquiry : 
TREVIRANUS believed that he was borne out in adopting a sameness 
of organic elements in all parts of the animal body, viz. globules 
and thin cylinders (elementary or primitive cylinders). According 
to others, these cylinders were by no means primitive, but consisted 
of globules arranged in a row: so that only globules, or round 
vesicles, remained for the elementary particles out of which, in fine, 
all the animal tissues were composed and formed. Subsequent 
enquiries proved, as indeed had been already surmised, that these 
vesicles were due merely to optical illusion?. Every one, who in- 
vestigates the tissues with the excellent microscopes of the present 
time, will easily convince himself, that such parts no where exist 
as ultimate elements of organic animal matter. 
Within the last few years, since regard has been paid in the 
investigation of the tissues to their origin and to their development, 
the problem has received quite a different treatment. That the 
tissues consist of different elementary parts, fibres, granules, cells, 
is plain from what has been said above; but it is another question 
whether these parts did not originally proceed from some common 
fundamental form, of which they are subsequent developments and 
modifications. Much had been already effected by scattered obser- 
vations, but to SCHWANN is the distinction due of having esta- 
blished the original cellular structure of the different tissues, and, at 
the same time, the great similarity between the microscopic struc- 
ture of Plants and Animals, of which Durrocnrer and Raspain 
had already a general notion®: our limits do not allow us to pro- 
pound his views, to which the name of Cell-Theory has been given, 
im detail. We will give an outline of them, in a few words, with 
a notice of the modifications which, from later researches, they 
would seem to require. 
The first elements of organic beings are cells. They have their 
1 See Vermischte Schriften anatomischen und physiologischen Inhalts von G. R. und 
L, C. TREVIRANUS. 4to. 1. Gottingen, 1816. s.117—144. Ueber die organische Elemente 
der thiereschen Kérper. 
7 Mitne Epwarps. Recherches microscopiques sur la structure intime des tissus 
organiques des Animaux, Annales des Sc. natur. IX. 1826, p. 362—394. Pl. 50. 
3 Mikroskopische Untersuchungen iiber die Uebereinstimmung in der Struktur und 
dem Wachsthum der Thiere und Paanzen von DR TH, Scuwanny. Berlin, 1839. Svo. 
VOL. I. 2 
