240 



THE PATHOGENIC FLAGELLATES 



thelial cells. When such blood is sucked into the digestive tract of 

 a bedbug the cell bodies of leukocytes and macrophages are broken 

 down and their contained parasites liberated. Patton found that the 

 parasites thus introduced into male or female bugs could remain in the 

 mid-gut for at least five days before beginning to develop, although 

 the majority of them are well under process of development by the 

 second or third day. 



Development of the parasite begins with a well-marked increase in 

 volume, and the cell nucleus (trophonucleus) early divides. This 

 process of division is not described in great detail by Patton, but it is 

 evidently similar to the process of mitosis of the euglena type. The 

 cell then rapidly undergoes flagellation, a pink staining (with Giemsa) 

 area being the seat of flagellum formation. This area was noted by 

 other observers and called the "flagellar vacuole" (Leishman, Patton), 

 the " vacuole-like area" (Christophers), and the "eosin body" 



Fig. 94 



Herpetomonas donovani, unequal division to form slender flagellated individuals. 



(After Leishman.) 



(Rogers), and is probably the same organoid of the cell that Kent 

 ('81) described as the contractile vacuole in his characterization of 

 the genus herpetomonas. This enlarged flagellar vacuole passes to the 

 cell periphery, where it bursts and a small "brush" of pink-staining 

 fibers protrudes from the cell, and these, later, by coalescence, form 

 the definitive flagellum. In other cases the parasites do not undergo 

 division in this manner, but the nucleus divides and the blepharoplast 

 divides two or three times, and eight flagella are formed at various 

 points on the cell periphery. These so-called "rosettes" divide to 

 form elongated flagellates as many in number as there are flagella 

 and blepharbplasts. The size of the flagellates varies considerably from 

 relatively long ones (up to 20 microns), by continued division, to 

 minute spirilla-like forms. 



