DEPARTMENT OF EMBRYOLOGY. 



69 



regarded as alive so long as they reacted specifically to neutral red and so long 

 as the nucleus remained homogeneous, without trace of a nuclear membrane. 

 Series I shows a small fragment of tissue aseptically removed and kept in a 

 moist chamber on ice; II, small fragments of tissue kept at room temperature 

 in neutral-red solution; III, entire animal kept on ice; IV, entire animal 

 kept at room temperature. 



Large macrophages 



Tracheal cartilage 



Kidney epithelium 



Smooth muscle 



Salivary gland epithelium . 



Bladder 



Tracheal epithelium 



Tongue epithelium 



Endothelium 



Small lymphocytes 



Large lymphocytes 



Microcytes 



Lung epithelium 



Leucocytes 



Kupffer cells 



Brain macrophages . . . . 

 Pancreatic epithelium . . 

 Red blood-corpuscles. . 



Liver cells 



Sertoli cells 



Mesenchyme 



Ovarian follicular cells . 



Uterine epithelium 



Uterine gland cells 



Epididymis epithelium . 



Adrenal cells 



Fat 



Intestinal epithelium . . . 



Nerve cells 



Skeletal muscle 



Heart muscle 



Series. 



I. 



hrs. 



96 



96 



72 



96 



96 



72 



72 



72 



72 



48 



24 























II. 



hrs. 

 48 

 49 

 24 

 15 

 12 

 72 

 30 

 53 

 24 

 18 

 32 

 18 

 18 

 1 

 

 



III. 



hrs. 

 96 



IV. 



hrs. 

 1 



Ingestion and Destruction op Bacteria by Connective-Tissue Cells. 

 In previous reports I have referred to investigations of Mrs. M. R. Lewis 

 and her coworkers in this laboratory, tending to show that the protoplasm 

 of living connective-tissue cells possesses an intense digestive power which 

 is capable of breaking down foreign bodies, such as melanin-pigment granules, 

 white of egg, red blood-cells, avian tubercle bacilli. Bacillus tumefaciens, and 

 various other organisms. During the past year Mrs. Lewis has experimented 

 with an organism {Bacillus radicicola) that ordinarily h'ves and multiplies in 

 living protoplasm inside of certain cells of the legumes. She found that these 

 organisms, although able to survive within the plant cell, were promptly 

 ingested and destroyed by the connective-tissue cells when inoculated into 

 tissue-cultures from chick embryos. Those not ingested, but simply lying 

 against a cell, were not destroyed or apparently affected, showing that the 

 strong chemical action of this particular protoplasm is limited by the cell 

 membrane. She further finds that the power of digesting the organism seems 

 to be in the homogeneous cytoplasm and not in the specific granules or 

 vacuoles. While these experiments were prosecuted for the purpose of learn- 

 ing more definitely the nature of the processes of the living cell, they have 

 at the same time a bearing that may be of importance to the pathologist, 

 particularly with reference to phagocytosis. This function has been ascribed 

 by the pathologist almost wholly to leucocj-tes. From the great number of 

 organisms and other foreign bodies which the connective-tissue cells are able 

 to destroy in tissue-cultures, we may conclude that these cells play a larger 

 part in phagocytosis than has been supposed, and it may be that the rapidity 



