ANIMAL TISSUES. 17 



tissues proceed originally from homogeneous elements. FONTANA, 

 and afterwards TREVIRANUS, busied themselves with this enquiry : 

 TREVIEANUS 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) l . 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 2 . 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 stnu> 

 ture of Plants and Animals, of which DUTROCHET and KASPAIL 

 had already a general notion 3 : our limits do not allow us to pro- 

 pound his views, to which the name of Cell-Theory has been given, 

 in 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 Vermisckte Schriften anatomischen und physiologischen Inhalts von G. R. und 

 L. C. TREVIRANUS. 4to. i. Gottingen, 1816. s. 117 144. Ueber die organische Elemcnte 

 der thiereschen Korper. 



2 MILNE EDWARDS. Recherches microscopiques sur la structure intime des tissus 

 organiques dcs Animaux. Annales des Sc. natur. IX. 1826, p. 362 394. PI. 50. 



3 Mikroskopische Untersuchungen uber die Uebcrcinstimmung in der Struktur und 

 dcm Wachsthum der Thicre und Pflanzen von DR TH. SCHWANN. Berlin, 1839. 8vo. 



VOL. I. 2 



