650 Journal of Applied Microscopy. 



The writer believes these bodies to be derived from the protoplasm of the 

 epithelial cells as the result of the specific action of the vaccine virus. This 

 explanation is opposed to that of Salmon, who believes them to be masses of 

 chromatin derived from leucocytes, and to that of Guarnieri and L. Pfeiffer, 

 both of whom regard them as protozoa which are multiplying in the tissues. 

 Still others think they are formed from the nuclei of epithelial cells. 



The writer says that while his work throws no light on the nature of vaccine 

 virus, it clears up the nature of the so-called vaccine bodies. 



The work is beautifully illustrated by four double-page colored plates contain- 

 ing 179 figures. R. m. p. 



Birch-Hirschfeld, Arth., und Garten, S. Ueber Cells of young embryos were intro- 

 das Verhalten in plantirter embryonaler , , . ^ , ,^ . , r ^, 



Zellen im envachsenen Thierkorper. Beit- ^uced mto adult animals of the same 

 riige zur Path. Anat. und Allg. Path., 26-1, species. Rabbits and their embryos 

 P- 3-. - P a es. were used chiefly, but chickens, goats, 



salamanders, and frogs were also tried. 



Very young embryos were used on account of the greater capacity of their 

 cells for proliferation, and also because it was desirable to determine whether it 

 was possible for a differentiation of cells to take place after transplantation. 



The embryos were teased out in salt solution, and the resulting mixture under 

 aseptic precautions was repeatedly injected directly into the liver which had 

 been exposed by abdominal incision. The liver was selected on account of the 

 excellent nourishment afforded by its abundant blood supply, and also on 

 account of the ease with which new tissue could be differentiated. 



Injections into the portal vein were tried, but abandoned, as death invariably 

 resulted from thrombosis. 



The results were controlled by injecting into animals of the same age em- 

 bryonic cells which had been killed by boiling. 



Positive results were obtained in more than one-fourth of the cases. The 

 most frequent result was the formation of cartilaginous nodules of the size of a 

 pea or smaller. As these nodules did not occur normally in animals of the same 

 age and size, the writers argue that a differentiation had taken place. 



Cartilaginous nodules were found in the periphery of the lung, evidently as 

 the result of embolism. Some of these nodules showed calcification. 



In order to test the effect of altered conditions in the liver, a sterile platinum 

 wire was passed through the liver, and at its ends silver electrodes were sewed 

 to the abdominal wall. Through this wire a current sufficient to warm it was 

 passed for five minutes each day. As a result, proliferation was more marked. 

 Adenoid tissue, epithelial-like cells, and pigmented cells were found in addition 

 to cartilage. 



Giant cells apparently due to irritation of foreign material were frequently 

 seen. After a time the nodules began to be absorbed, and finally disappeared. 



The writers arrived at the following conclusions : 



Embryonic cells differentiate after implantation. The greatest differentia- 

 tion occurs when very young cells are implanted. 



This differentiation is a specific property of the cell, and is not dependent 



