454 J. R. BRADFORD AND H. G. PLIMMEK. 



seen are those shown in figs. 1 — 6. The body of the organism 

 is stained blue, but not uniformly, there being parts which are 

 stained faintly, and some hardly at all, which is in confirmation 

 of the alveolar structure which has been mentioned above. 

 The macronucleus is stained a pinkish-red, and is, in the 

 resting form, nearly homogeneous, with only traces of a 

 reticular structure ; it is also sharply defined and extends 

 right across the short axis of the body. The micronucleus 

 is stained of a darker red colour, and it al\va3'S stains more 

 intensely than any other part of the organism : it appears as 

 a very small round dot, and we have been unable, wirdi the 

 highest powers, to make out any further structures in it. It 

 is generally surrounded by an unstained halo. The flagellum 

 is stained of a yellowish-pink colour, as well as the edge of 

 the undulating membrane, which can be seen to end in the 

 micronucleus. The edge of this membrane is apparently 

 thickened and merges into the flagellum. In some organisms 

 the part of the body behind the micronucleus stains of a 

 darker blue than the rest of the body, and the darker part 

 may contain a row of faint dots arranged regularly in the 

 long axis of the organism. These are seen especially in those 

 animals from which the spleen has been previously removed. 



Besides these forms, the first of which constitutes by far 

 the greater part of those seen in the blood, there are other 

 adult forms which are seen at certain times and in certain 

 places. That shown in fig. 5 is seen in the blood of the rat 

 when the disease is well advanced, about a day or two before 

 death, and they are also found in the blood of spleenless rats 

 from the second day ; they are also seen in the blood of the 

 mouse, and in greater numbers especially in the blood from 

 the lungs taken immediately after death. This organism is 

 much larger than the ordinary adult form, and is much wider, 

 often more than double the width, and is more irregular in 

 shape. The protoplasm is quite homogeneous and much more 

 delicate, and it stains very faintly with the methylen blue. 

 The macronucleus is large and roundish in shape, and the 

 chromatin is more condensed at the circumference, so as to 



