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Prof. E. Goldmann. On a New Method of [Feb. 22, 



peritoneum, also reaches the peritoneal cavity, where even in its vitally 

 stained condition it becomes the " macrophage " par excellence, absorbing not 

 alone dead material, such as carmine, dust, etc., but also living tubercle 

 bacilli, manifesting a predilection for those of the avian type. 



The importance of these cells will be fully illustrated by our inquiries 

 into pathological conditions, such as tuberculosis and malignant growths. 



By means of the intra-vitam stain we can differentiate the " Kupffer " 

 star cell in the liver, the reticulum cell of lymph glands, spleen, and bone- 

 marrow, the interstitial cell of the testicle, the follicular cell in the maturing 

 Graafian follicle, the cortex cell of the suprarenal, the epithelial cells of the 

 choroid plexus, the epithelial lining of the convoluted tubes of the kidney. 

 Most striking is the appearance of the placenta and its behaviour in relation 

 to the rest of the body. When pregnancy occurs in the vitally stained 

 animal, the blue colour disappears from its skin and is concentrated in the 

 uterus, the latter forming a centre of attraction for the vital stain, and 

 actually dispossessing the remaining tissues of their blue. In the uterus we 

 find the blue chiefly in the free cells of the decidua serotina, but also in the 

 cells of the reflexa during the period of its existence. 



In the first days of pregnancy, during which the development of the 

 mouse and rat embryo is slow and its growth is solely dependent upon 

 exuded maternal blood, I have recently found that peritoneal pyrrhol cells 

 migrate into the uterine wall, penetrate into the primitive placenta and cast 

 off vitally stained granules, which are snatched up by foetal cells in the way 

 of nutritive material. Once the placenta has attained its maturity we 

 discover the vital stain in the " giant cells," which form the boundary line 

 between the maternal and foetal part of the placenta. We also find it in 

 those foetal cells which constitute the only barrier between the maternal 

 blood spaces and the- endothelial lined capillaries of the foetus. Finally, the 

 vital stain effects a most striking specific differentiation in the granulated 

 cells of the vitelline membrane. Notwithstanding the fact that the yolk 

 membrane is deeply stained throughout its whole extent, and the placental 

 fluid shows a faint bluish colour, the embryo remains perfectly colourless, 

 the placenta and its appendages thus forming a kind of protective barrier 

 against the passage of the stain from the maternal into the foetal organs. 



As to the later stages of embryonic growth my new histo-chemical studies 

 have proved that exactly the same foetal cells of the placenta, which so 

 vigorously absorb the vital stain, store also glycogen, fat, and haemoglobin 

 temporarily, ere these substances pass into the foetal circulation. In the 

 light of my new work the importance of vital staining for the purposes of 

 embryological research will become more apparent. 



