80 



raiyphi A. in suspension in saline solution and killed in 

 a water-bath at 62oC. during an hour. 



May 12 th 1921 -Rabbit was killed by violent narco- 

 sis with chloroform (death took place in 1.20 mins). 



Histologic study— Under a weak po- 

 wer the bone-marrow is s.en to be rt Ir 

 in cells, less so however than under 

 normal conditions; the regularly distri- 

 buted vacuoles which in normal bone- 

 marrow correspond to fat-cells appear 

 to be wanting. 



Under a strong power, the fat cells 

 are seen to be reduced in volume and 

 have to a certain extent disappeared; 

 here and there a fat-cell strongly redu- 

 ced in volume and with its nucleus 

 migrated towards the centre is to be 

 seen; almost always the part of the 

 reticulum round it is strongly stained 

 by eosin. 



There is no congestion. 



The œdema of the reticulum is less 

 marked than in the preceding rabbits; 

 it is confined to certain parts of the 

 reticulum whicli are intensely stained 

 by eosin. 



Of parenchyma cells, the most nu- 

 merous are polymorphonuclear leucocy- 

 tes which quite mask the rt^maining 

 parenchyma cells. 



Erythrogenetic groups are in evi- 

 dence. 



Megalocaryocytes with nofinal appe- 

 arance and distribution. 



Examining sections from different 

 J>locks, I noticed slight modifications of 

 the aspect indicated; in some points 

 there was more accentuated oedema and 

 parenchyma cells were less numerous. 



7th. Day of Immunisation. 



Rabbit 218-Weifbt 13» gi». 



Inoculated in marginal vein of ear with 1 cc of a 

 suspension of B. paratyphi A. (liquid A) at 3.30 p. m. 

 on April 7 th 1920. 



Pound dead on April 4 th 1920. Necropsied when 

 still well preserved. 



Autopsy.— The bone-marrow (femur, both sides) shows 

 firm consistence and a shining surface; colour is brick 

 red and fine granulations, white and réfringent, are to 

 visible. 



Histologic study.— -Vndev a weak po- 

 wer the appearance of the bone manow 

 is entirely different from the normal. 



Capillaries are dilated and tilled with 

 red blood corpuscles (Fig. 13, Plate 22). 



The parenchyma cells, which are 

 numerous, show a tendency to group 

 themselves along the capillaries (Fig. 13, 

 Plate 22.) 



Under a strong power the myelo- 

 cytes arc seen to be the dominant cle- 

 ment. Not only do amphophil myelo- 

 cytes con.slitute the majority of the cells 

 found round the vessels but they also 

 form groups of 4 or 6 cells in the pa- 

 renchyma, between tîie capillaries, where 

 they place themselves over the fat-cells 

 (Fig. 16b, Piale 17:; in the latter case 

 they have the appearance of a group 

 of cells (myelocytes) surrounded by a 

 clear halo (.body of the fal-cellV 



Other fat-cells have approximately 

 normal dimensions (Fig. 16a, Plate 17). 



Polymorphonuclear leucocytes are 

 scarce. Lymphocytes are not plentiful; 

 they are found mostly round the small 

 arteries. 



The haemoglobin-containing elements 

 affect a grouped disposition ; these groups 

 are formed by few cells and arc much 

 less conspicuous than the ones of mye- 

 locytes; it is easy to find erythroblasts 

 with kanjorrhexis. 



Myelocytes are as numerous as in 

 the normal organ; many of them con- 

 tain phagocyled granulocytes. 



Foci made up of big cells with an 

 elongated nucleus and sometimes jiarro 

 wing towards the middle (shape of a 

 figure 8), witli little chromatin, which 

 I take to be connective tissues cells, are 

 often seen in the sections. Only once 

 and again do these foci contain any 

 other cells besides connective tissue 

 cells; sometimes a granulocyte someti- 

 mes non-granular mononuclear leucocy- 

 tes. 



