No. I.] BLOOD CORPUSCLES. gl 



constant. His results were not striking, but were sufficient to 

 convince him that the spleen has a distinct though subordinate 

 part to play in the production of red corpuscles. As proof that 

 the lymph glands also produce red corpuscles, he cites an ex- 

 periment in which the thoracic duct was ligated for thirty-seven 

 days before the animal was killed. Post-mortem examination 

 showed that some of the lymph glands, especially those of the 

 mesentery, had a reddish appearance, and contained a number 

 of nucleated red corpuscles. Moreover, enumeration of the red 

 corpuscles of the blood of this animal proved that a diminu- 

 tion of about 13 per cent, had taken place. Gibson's theoretical 

 views of the way in which the red corpuscles are formed are as 

 follows : In some of the colorless marrow cells the nucleus 

 begins to increase in size, while haemoglobin develops in the 

 body of the cell. Later, as the haemoglobin becomes fully 

 formed, the cell shows a diminution in size which affects the 

 nucleus also, so that finally one of the small typical nucleated 

 red corpuscles is produced. Just how this becomes changed to 

 the non-nucleated corpuscle is not stated very clearly. In one 

 place he seems to agree with the view of Kolliker and Neu- 

 mann that the nucleus fragments and is absorbed, while in 

 other places he speaks of the nucleus becoming a blood plate. 

 He describes the blood plates under the name of " colorless 

 microcytes," and thinks that they are formed in part from the 

 fragmented nuclei of the white corpuscles and in part from the 

 fragmented nuclei of the nucleated red corpuscles. In addition 

 to the "colorless microcytes," he describes in the blood what 

 he calls "colored microcytes," which he believes to be the same 

 as the " haematoblasts " of Hayem. These he considers to be 

 simply fragments of red corpuscles formed in some way or 

 other in the circulating blood. Gibson seems to be describing 

 here the microcyte of pathological literature, small, spherical, 

 deeply colored corpuscles very common in the blood in progres- 

 sive pernicious anaemia, leukaemia, chlorosis, etc. [See Osier 

 (24), Laache (25), Eichorst (34), et a/.] 



Obrastzow's (35) theory bears some resemblance to that of 

 Olser already described. The nucleated red corpuscles are 

 derived from colorless cells, which in turn are formed from free 

 nuclei, or little spheres of nuclear matter (protoleucocytes), each 

 of which develops round itself a layer of protoplasm. The 



