104 PATHOGENIC BACTERIA. 



organisms in general, and specific organisms. 3. There 

 are no essential differences in the growth on the various 

 media except in vegetation. 4. There are no differences 

 in morphology shown by the test-organisms. 



Wauters comes to somewhat different results. He col- 

 lected leukocytes by injecting staphylococci into the pleu- 

 ral cavity of a rabbit. The exudate was collected, titrated, 

 and mixed with blood serum previously heated to 6o° C. 

 After an hour the mixture was centrifugated, the liquid 

 part removed and replaced by an equal quantity of dis- 

 tilled water. After an hour this also was centrifugated. 

 He found that bacteria grew well in the plain heated 

 serum and in the watery extract of the leukocytes, but 

 not in the serous extract of the leukocytes. Of the 

 lymphoid organs, Wauters found the extract of bone mar- 

 row to be about twenty times as bactericidally powerful 

 as a similar extract of lymphatic glands, and very much 

 more powerful than extracts of the solitary follicles, vermi- 

 form appendix, and spleen. Of the organs other than 

 lymphoid, extracts from the brain, striped muscles, and 

 thymus were capable of restraining bacterial growth 

 for a time only; extracts of the liver, kidney, pancreas, 

 adrenal, and testicle were found to possess bactericidal 

 activities varying in wide limits according to the animal 

 from which they are taken, while extracts of the lung and 

 connective tissues were found to be very active. Of all 

 the tissues, the bone marrow was most active. Wauters 

 found that the erythrocytes and fatty tissue contained 

 in the marrow were bactericidally inert, so that the vir- 

 tue resided exclusively in the leukocytes. Inasmuch as 

 the lymphocytes seem devoid of bactericidal powers, as 

 is shown by the very feeble activity of extracts of the 

 lymph-glands, the active substances must be present in 

 the ameboid cells found in the bone marrow. The bac- 

 tericidal power of the tissues may depend in large part 

 upon leukocytes and similar cells, as is evinced by the 

 observation that tissues most likely to contain consider- 

 able numbers of leukocytes are most actively germicidal. 



