280 Scientific Proceedings (116). 



great practical importance in so far as the explanation of the 

 occurrence of rickets in the human being is concerned. 



5. Cod liver oil, on the contrary, as our experiments have re- 

 peatedly shown, is powerful in its anti-rachitic properties. 



141 (1723) 



Subcutaneous tubes for chemotactic studies and 

 leucocyte collection. 



By FREDERICK L. GATES. 



[From the Rockefeller Institute for Medical Research, New York City.] 



For the study of the chemotactic influences of various sub- 

 stances, including bacteria and their products, and for the collec- 

 tion of phagocytes and other wandering cells, small glass test 

 tubes of about 5 c.c. capacity have been placed in the loose sub- 

 cutaneous tissues of the rabbit. The procedure is as follows. 



The mouths of test tubes, 1.2 X 5 cm., are covered with drum 

 heads of fine bolting silk, tied on with thread, which permit free 

 interchange of liquids with the subcutaneous tissues and the migra- 

 tion of cells and bacteria. The chemotactic material or the or- 

 ganism to be studied, either in agar (1 c.c.) overlaid with Ring- 

 er's solution, or in fluid form is then added to the sterilized tubes 

 through a hollow needle. A tube may be placed in each flank 

 through a single dorsal incision, after blunt dissection of the loose 

 subcutaneous tissue. Surgical anesthesia and asepsis are required 

 for the operation. Removal of the tube contents is accomplished 

 by hypodermic puncture through the cloth heads of the tubes, 

 after careful cleansing of the skin with iodine and alcohol. The 

 needles of two 20 c.c. syringes are plunged into the tube. One 

 syringe is already rilled with Ringer's solution or other liquidto 

 replace the tube contents as it is drawn into the second syringe. 

 Thus the tube is washed out and left full of fresh material. The 

 tubes themselves are practically non-irritating and their contents 

 may be recovered daily, or at longer intervals, for weeks or 

 months. 



