2718 Journal of Applied Microscopy 



myelogenous leukaemia and that this increase of mast cells is of even greater 

 diagnostic importance than the increase of eosinophils. Shortly before death, 

 however, the total number of mast cells became markedly increased. Until 

 near the end of the disease there was only slight enlargement of the spleen, and 

 the total number of leucocytes scarcely exceeded the physiological limit. 

 Myelocytes were present in the blood and the number increased with the advance 

 of the disease. During the last six months of illness myelocytes formed from 30 

 to 50 per cent, of the leucocytes. This case and the one reported by L. Michaelis 

 illustrate the fact that the appearance in the blood of myelocytes rather than an 

 increase in the total number of leucocytes is the characteristic feature of the 

 disease. Shortly before death the leucocyte count rose to 110,000. 



Large mononuclear cells devoid of granules and distinctly different from the 

 large mononuclear leucocytes of the blood appeared in large number toward the 

 end of the illness when no less than 54 per cent, of all the leucocytes belonged 

 to this type. Nageli claims that these cells are found in the blood in every case 

 of myelogenous leukaemia and he noted also that they may in the later stages of 

 the disease form the predominating leucocyte in the blood. Nageli regards them 

 as specific bone marrow cells and the antecedents of Ehrlich's myelocytes. For 

 the study of the mononuclear non-granular elements in the blood the eosinate of 

 methylene blue should be used, as Ehrlich's triple stain does not differentiate the 

 lymphoid cells. j. h. p. 



CURRENT BACTERIOLOGICAL LITERATURE. 



H. W. CONN, Wesleyan University. 



Separates of Papers and Books on Bacteriology should be Sent for Review to H. W. Conn, 

 Wesleyan University, Middletown, Conn. 



Among the many papers presented at the fourth meeting of the American 

 Society of Bacteriology were the following on bacteriological methods, outlines 

 of which may be found in Science, March 6, 1903, and in Cent. f. Bact. II, p. 381. 



Dunham. The Influence of Physical Condi- Observations have convinced the 

 tions on the Character of Colonies on ... 



Gelatin Plates. author that the character of colonies in 



gelatin varies with conditions. The same bacteria may produce colonies wholly 

 unlike and different species of bacteria may produce colonies indistinguishable 

 from each other. This led him to testing the effect of varying the physical con- 

 dition of the gelatin upon the colonies of B. typhosus and B. dysefitarice. He 

 finds that the stiffness of the gelatin has a profound effect upon the character 

 of the colonies, especially upon the deep lying colonies. In thin gelatin the col- 

 onies of typhoid have a tendency to form closely aggregated masses of small 

 colonies which do not appear in denser gelatin and that other great differences 

 appear. He finds, as would be expected, that the stiffness of gelatin varies with 

 the grade of gelatin used, but also that it varies greatly according to the amount 

 of heating which is received. Even the question of the cooling of the gelatin 



