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SUMMARY OF CURRENT RESEARCHES RELATING TO 
circulation generally, but especially in the bsematopoetic organs, the 
liver, spleen, and osseous medulla. The proliferation of blood-cells is 
favoured by physiological influence. Multiplication also goes on in 
other vasculat regions where blood pressure is very feeble ; as at the 
level of the venous capillaries of the area vasculosa, in the capillaries 
of the buds of the lower limbs, in the interior of the capillaries of all 
the visceral organs, near those of the subcutaneous tissue, and in those 
which are near the central nervous system. 
The red corpuscles of mammals owe their origin to erythroblasts 
whose nucleus has left the cell, and undergone, later on, an extracellular, 
or even an intracellular destruction. There is no relation between 
leucoblasts and erythroblasts ; they present distinct characters in all 
stages of their development. All the blood-cells multiply by mitosis ; 
the erythroblasts when undergoing indirect division may be recognized 
by a delicate border of homogeneous protoplasm. The leucoblasts are 
recognizable by the existence of a wider zone of protoplasm, similar to 
that which characterizes these elements when in a state of repose. 
Leucoblasts with eosinophilous granulations are formed at the expense 
of white cells with finely granular protoplasm, or at that of leucoblasts 
with eosinophilous granulations which are ready to multiply by mitosic 
division. 
Cells with budding nuclei are only met with in the hsematopoetic 
organs of Mammals. They do not take any direct part in the formation 
of the red corpuscles. They absorb nuclei and the debris of erythro- 
blastic nuclei, and contribute to the formation of adenoid tissue, in the 
meshes of which the blood-cells multiply and develope. 
Two kinds of giant-cells are found in the hsematopoetic organs of 
Mammals. Some of the megalocaryocytes have abundance of proto- 
plasm ; these should be regarded as elements which have still to fulfil 
the functions of phagocytosis and the formation of adenoid tissue. 
Others have little protoplasm and a very chromatic nucleus, and should 
be considered as elements which have reached the last stage of life, 
and whose protoplasm has been used up. 
The adenoid tissue which serves as the framework for the blood- 
corpuscle in several bsematopoetic organs arises at the expense of a 
variety of the white globules. These give off ramified prolongations 
which anastomose with adjacent prolongations. In the bsematopoetic 
organs of Mammals the giant-cells also contribute to the formation of 
this trabecular system. 
The liver of Mammals passes through three stages ; in the primitive 
stage it is formed of a reticulum of cellular hepatic tubes, and in the 
meshes of this the blood circulates. Young blood-cells stop in it and 
multiply by indirect division. This primitive stage is persistent in the 
Amphibia. The second is a truly embryonic stage, in which the liver 
may be considered as a true hsematopoetic organ, just as much as the 
osseous medulla. New blood-forming capillaries appear in the interior 
of the hepatic cords, where they form white and red corpuscles. In 
the final stage the liver takes no part in the formation of blood. 
Three stages may likewise be distinguished in the development of 
the spleen. In the first stage there is no differentiation into splenic 
pulp and Malpighian corpuscles. The erythroblasts and the leucoblasts 
