PROTOZOA 387 



Bowhill 4 : (1) large and small spherical forms, karyosome, 

 situated at edge of parasite; (2) large and small pyriform 

 parasites single and in pairs; (3) large and small rod-like 

 bodies, some of them extending across the entire diameter of 

 the corpuscle, sometimes in pairs; (4) rosette form, consisting 

 of four bodies connected in the center by fine threads, each 

 body usually containing a karyosome at its extremity; (5) 

 flagellate forms. 



Laveran found multiplying forms more common in the 

 spleen than in peripheral blood. They multiply by direct di- 

 vision, usually into two, sometimes into four bodies. The 

 karyosome elongates, then divides into two parts; these sepa- 

 rate, followed by division of the cell body. The two parasites 

 often divide, giving four, within the red corpuscle. Some- 

 times the karyosome divides into four parts before the proto- 

 plasm divi'des. The disposition in fours is one of the most 

 striking morphological characters of Piroplasma equi (La- 

 veran). 



The number of parasites in the peripheral blood varies a 

 great deal. They are present during febrile stages but dis- 

 appear after the fall of temperature. During the stage of 

 high fever they are numerous. Theiler found them in un- 

 stained blood as abundant as one parasite in from 5 to 40 red 

 corpuscles. Williams states that the number of parasites in 

 the peripheral blood is proportional to the severity of the 

 disease and that from 1 to 10 per cent or up to 30 per cent of 

 the corpuscles may be infected. Baruchello and Mori state 

 that the parasites are found most easily during the early 

 stages of the disease. The "rosette" form is present in vary- 

 ing numbers. Sometimes the parasites are so scarce as to be 

 found only after a long search. After the administration of 

 quinine the rosettes are very scarce (Theiler). With the fall 

 of temperature the number of parasites decreases from day to 

 day ; by the time the temperature has fallen they can be 

 found only with difficulty. 



4 Bowhill. Jour, of Hyg., Vol. V (1905) p. 7. 



