and Laboratory Methods. 2583 



was, in outline, as follows : a small portion of some gland, usually one of the 

 salivary glands, was excised under as nearly as possible aseptic conditions. 

 The piece of tissue was then kept out of the body and exposed to the environ- 

 mental condition it was desired to test (e. g., heat, cold, chemical agents, etc.). 

 Then it was transplanted into the kidney or under the peritoneum of the same 

 animal, or some other animal of the same species. After some days the area of 

 transplantation was removed and sectioned, and search was made for evidence 

 of regeneration in the transplanted tissue. The occurrence of regeneration was, 

 of course, proof that the tissue had successfully withstood the environmental 

 difficulties. The animals used were rabbits. Examples of the results obtained 

 follow. A piece of salivary gland kept dry in a refrigerator for 43 hours showed 

 regeneration after transplantation. A similar piece kept moist in a refrigerator 

 for 54)'2 hours showed regeneration. Experiments with mammary gland tissue 

 and with pieces of the pancreas failed entirely. A piece of testis showed regen- 

 eration after a stay of 48 hours in a refrigerator. Experiments in which the 

 pieces of tissue were immersed in chloroform or in formalin (lU per cent.!) failed 

 to give positive results. Pieces of salivary gland and of testis after exposure 

 for from 15 to 20 minutes to a temperature of 60° C, showed marked regener- 

 ating capacity. A piece of salivary gland regenerated after 45 minutes expos- 

 ure to a temperature of — 21° C, and pieces of testis showed similar resisting 

 power to such extreme cold. Pieces of the same tissue solidly frozen on the 

 stage of a freezing microtome regenerated. These results bring out very forci- 

 bly the fact that maximum and minimum temperatures within which life is possi- 

 ble are very different for the cell and for the organism as a whole. r. p. 



NORMAL AND PATHOLOGICAL HISTOLOGY. 



JOSEPH H. PRATT, Harvard University Medical School. 



Books for Review and Separates of Papers on these Subjects should be Sent to Joseph H. Pratt, 

 Harvard University Medical School, Boston, Mass. 



Wechsberg, F. Beitrag zur Lehre von der pri- Baumgarten has maintained that the 

 maren Einwirkung des Tuberkelbacillus. production of miliary tubercles and 

 Ziegler's Beitrage. 29: 203-232,1901. ^ • , 1 



diffuse tuberculous tissue is the result 



of a direct irritation by the tubercle bacillus of the fixed cells of the part. This 



irritation causes the cells to proliferate. 



According to Weigert's well known theory such an explanation would not be 

 tenable. The cause of the proliferation of the cells should be sought rather in 

 an injury to the tissue which removes the inhibitory force that normally holds 

 the power of growth of the cells in check. Neither Baumgarten nor the other 

 writers have concerned themselves with the existence of such a primary injuiy. 



Wechsberg studied this problem in Weigert's laboratory. Suspensions of 

 tubercle bacilli were injected into the ear veins of rabbits. The animals were 

 killed at different periods, ranging from six hours to twelve days, and the lungs 

 hardened and sectioned. 



