Volume 1

A textbook of human physiology / / translated from [the] 7th German edition by William Stirling.

  • Landois, Leonard
Date:
1891
Catalogue details

Licence: Public Domain Mark

Credit: A textbook of human physiology / / translated from [the] 7th German edition by William Stirling. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

    51/602 (page 11)
    I I brown or green opalescent blood with colourless corpuscles (amceboid cells) ^^^J' andTome crabs the blood is blue, owing to the presence of a colouring matter (hsemocyamn), Size (jt=0-001 Millimetre) Of the Disc-shaped Corpuscles. Of the Elliptical Corpuscles. Short Diameter. Long Diameter. Elephant, . . 9-4 fi Man, . .7-7,, Dog, . . . 7*3,, Rabbit, . . 6'9„ Cat, . . . <3-5„ Sheep, . . 5'0,, Goat, . . . 4-l ,, Musk-deer, . . 2 5 ,, Llama, . . i'O fi Dove, . . • 6'5 ,, Frog, . . . 15-7 ,, Triton, . . 19*5 ,, Proteus, . . 35-0,, The corpuscles of Amphiun than those of Proteus (Riddel 8-0 fi U-7 „ 22 3 ,, 29-3 „ 58-0 ,, ta are nearly one-third larger ). 7. ORIGIN OF THE RED BLOOD-CORPUSCLES.—(A) During Embryonic Life.—Blood-corpuscles are developed in the fowl during the first days of em- bryonic life. [They appear in groups within the large branched cells of the mesoblast, in the vascular area of the blastoderm outside the developing body of the chick, where they form the blood-islands of Pander. The mother-cells form an irregular network by the union of the processes of adjoining cells, and meantime the central masses split up, and the nuclei multiply. The small nucleated masses of protoplasm, which represent the blood-corpuscles, acquire a reddish hue, while the surrounding protoplasm, and also that of the processes, becomes vacuolated or hollowed out, constituting a branching system of canals; the outer part of the cells remaining with their nuclei to form the walls of the future blood-vessels. A fluid appears within this system of branched canals in which the corpuscles lie, and gradually a communication is established with the blood-vessels developed in connection with the heart. According to Klein, the nuclei of the protoplasmic wall also proliferate, and give rise to new cells, which are washed away to form blood-corpuscles.] At first the corpuscles exhibit amoeboid movements, are devoid of pigment, nucleated, globular, larger and more irregular than the permanent corpuscles. They become coloured, retain their nucleus, and are capable of undergoing multiplication by division; Reniak observed all the stages of the process of division, which is best seen from the 3rd to the 5th day of incubation. Increase by division also takes place in the larvae of the salamander, triton, and toad (Flemming); and during the intra-uterine life of a mammal, in the spleen, bone-marrow, the liver, and the circulating blood (Bizzozero). Neumann found in the liver of the embryo protoplasmic cells containing red blood-corpuscles. Cells, some with, others without, haemoglobin, but with large nuclei, have been found. These cells increase by division, their nucleus shrivels, and they ultimately form blood-corpuscles (Lowit). The spleen is also regarded as a centre of their formation, but this seems to be the case only during embryonic life (Neumann). Here the red corpuscles are said to arise from yellow, round, nucleated cells, which represent transition forms. Foa and Salvioli found red corpuscles forming endogenously within large protoplasmic cells in lymphatic glands. In the later period of embryonic life the characteristic non-nucleated corpuscles seem to be developed from the nucleated corpuscles. The nucleus becomes smaller and smaller, breaks up, and gradually disappears. In the human (,|''.v<» ;it lowxth week only nucleated corpuscles are found; at the third month their number is still ]-i of the total corpuscles, while at the end of foetal