the Origin of Intestinal Worms, 329 



cells, and they might not inappropriately be designated pri- 

 mitive cellsy as they are the primary parts of all the systems of 

 the living body, changing by degrees into all the different 

 forms which the elementary particles of the different systems 

 assume. In plants these primitive cells are permanent in al- 

 most every part. The same is true in some of the systems of 

 animal bodies, as in the epidermis and all other parts of the 

 systema corneum, as also in the pigmenta. Very often a se- 

 cretion occurs vv^ithin the primitive cells, as is common in 

 plants ; and may be witnessed in great beauty in the pigmen- 

 tum of the eye ; in the mucus Malpighii of the negro, it has 

 been observed by Dr Henle of Berlin, as the dark colour 

 seated within the cells ; and I lately made the same observa- 

 tion in the very black cutaneous membrane of the Delphimis 

 Fhoccena. The secretion commonly begins near to the nucleus. 

 The nucleus generally disappears when the cells are fully de- 

 veloped ; but this is not the case in the pigmentum of the eye, 

 where the transparent nucleus looks like a hole in the dark 

 cell. All the parts belonging to the corneous system, the 

 epidermis, the nails, the horns, &c., consist merely of such 

 primitive cells, and they are invariably formed and produced 

 from a new mass or cytoblastema, secreted from the subjacent 

 living parts. 



The systems in which the primitive cells do not undergo 

 any further change, may be considered as possessing the 

 lowest degree of organization. The globules of the blood, 

 according to the observations of Professor Valentin, are to 

 be regarded as nuclei with nucleoli, the real cells of which 

 are dissolved in the transparent liquor of the blood. In 

 other systems the metamorphosis of these primitive cells is 

 much more striking. In the formation of cartilage, a secre- 

 tion takes place between the cells which enclose it, so that 

 they appear at last merely as small bodies, the corpuscula 

 of the cartilage, in its interior ; afterwards when the inter- 

 cellular substance is once filled with calcareous matter they 

 appear to be united by means of long very narrow tubes (see 

 a beautiful delineation by Professor Joh. Miiller, in Miescher 

 de Inflammatione Ossium, eorumque anatome generali, Berl. 

 183G), and at last are filled up with calcareous matter, and 



