BY 1!. (iUEIG SMITH. .'i,S9 



the case, the corpuscle is paler than usual. The amoeboid motion 

 is active with the smaller sizes, and slower with the larger. On 

 account of the amoeboid motion, the parasite may appear with 

 one, two, three or more protrusions; it ma}' divide into two, the 

 halves connected by a thread when an appearance is obtained 

 which is probably that described and considered by Theobald 

 Smith as a younger stage of the pear-shape. The two halves 

 join again to form perhaps a diamond or a sphere The two pear- 

 shaped forms are seldom small; they are generally large, and vary 

 from 2-5 to 4 /x long, b}' 1*5 to 2 /j. broad, and have a granule 

 near the swollen end. They may be considered to be in extremely 

 slow amoeboid motion, but so slow as to be practically non-motile 

 or as a particular stage in the developmental cycle. In suppoj't 

 of the former hypothesis there is the fact that long observation 

 showed the form to vary from the pear to an egg or round shape; 

 while in another case, also after long observation, an apiosoma 

 without altering its shape disappeared from the corpuscle (3). 



In very acute cases of the fever a few large granules have been 

 observed lying separated from one anothei- or in a heap within 

 some of the blood corpuscles. They are non-motile, and retain 

 their rounded shape. Their significance is unknown, ))ut it is 

 suggested that they may be spore forms (3). 



Besides the parasitic forms, one frequently observes in the blood, 

 red corpuscles larger than usual, rather pale and beset through- 

 out the diflferent layers with chromatin granules. Since these 

 granules are found in other cases of anaemia as, in the sheep, they 

 have no relation with the parasite, and are to be traced to the 

 caryolysis of the 3'oung red corpuscles. 



The complete life cycle of the parasite has not j^et been 

 described by any author. Theobald Smith suggests that the small 

 motile globule is the youngest intraglobular stage, the globule 

 dividing, each part becoming spindle-shaped and ultimately pear- 

 shaped, the portions being still connected b}' a thread. In the 

 chronic cases of the fever there is a certain immunity produced, 

 and the later stages of the parasite are suppressed (1) The large 

 pear-shaped body either within or without the corpuscle may begin 



