Nucleus of the Animal and Vegetable " Celt:" 229 



Pig. 49. Capillaries in the course of formation by cells derived from cor- 

 puscles of the blood, in the i-etina of a fcetal ox of 18 inches. These cells, while 

 still red (a), apply themselves together, so as to form a necklace-like object, 

 composed of elliptical beads ; and having coalesced, and become pale (/3), and 

 the membranous partitions having disappeared, they form a tube. Magnified 

 600 diameters.— (Phil. Trans. 1841, Plate XXIL, fig. 107). Nucleal centres or 

 orifices, forming communications apparently between the interior and exterior 

 of these vessels, are seen at 5 in two parts. 



Fig. 50, after Professor Goodsir (Anatomical and Pathological Observations, 

 1845, Plate I., fig. 11). " Diagram of mucous membrane of jejunum when ab- 

 sorption is not going on. a. Protective epithelium of a villus, h secreting epi- 

 thelium of a follicle, ccc primary membi*ane, with its germinal spots or nuclei 

 dd, e. Germs of absorbent vessels. /, Vessels and lacteals of villus." 



Fig. 51. From the Ox. Granules of the ovisac with their nucleus. In one 

 instance a single granule presents two nuclei. This granule measured tttf^^ 

 Paris line in length —(Phil. Trans., 1838, Plate VIII., fig. 73.) These granules 

 are cytoblasts ; exceedingly well seen in the ovisac : which contains little of 

 any thing besides, in a solid form. — (See the four Plates, V., VI., VII., VIII., 

 in the Phil. Trans, above referred to.) 



Fig. 52. Part of the ovum of the Common Leech, drawn by Professor E. II. 

 "Weber, of Leipzig (Ueber die Entwickelung des medicinischen Blutegels, in 

 Meckel's Archiv, 1828, Taf. X., fig. 7). See page 222 of this Journal. 



Fig. 53. Diagram to shew the probable mode of origin of epithelium cells. 

 (See p. 224). 



Fig. 54. From the Fallopian tube of the Rabbit, a, /3, 7, J, Bodies which seem 

 to have been the nuclei, cytoblasts, or cells, from a germinal membrane such as 

 that in the diagram, fig. 53. (Compare ^ in this figure with X. in fig. 53). 

 J, Young epithelium cells. (Compare with XI. in fig. 53). |, Fully formed 

 epithelium cells, with their cilia, n. Cells filled with cytoblasts. They seem 

 to represent parent-cells, giving origin to such bodies as those at 6, which are 

 obviously derived from corpuscles of the blood. /, Some of the latter {f), now 

 become cells with processes or arms ; which, interlacing, enter into the forma- 

 tion of X, the incipient chorion.— (Phil. Trans., 1840, Plates XXVIII., XXIX.) 



On the Precipitation of one Earth or Metallic Oxide by another 

 from Saline Solutions. By JoiiN Davy, M.D., F.R.S., 

 London and Edinburgh, Inspector-General of Army Hospi- 

 tals. Communicated by the Author. 



Though this, I believe to be a subject very deserving of 

 inquiry, as likely to throw light on many things in the eco- 

 nomy of Nature, and to lead to useful results applicable to 

 chemical analysis, it appears hitherto to have received but 

 little excepting incidental attention ; at least I am not ac- 



