206 ANNIE PORTER. 



fif,As. 76, 77). A '' plasmodial" i form (PI. 13, figs. 75, 77) is 

 thus assumed. The protoplasm collects around the nuclei, 

 and gradually fragmentation of the " plasmodium " occurs, 

 the result being the formation of a number of small bodies, 

 which rapidly round off, forming definite resting bodies (PI. 13, 

 figs. 78-81). Sometimes these resting bodies remain in 

 proximity to one another, so forming groups (PI. 13, figs. 80, 

 81). The parasites now measure only l"5/x to4yu long and 

 1 fx to 2'5 in broad. Sometimes one chromatic mass (PI. 13, 

 fig. 82) only can be distinguished. Often both nucleus and 

 blepharoplast (PI. 13, figs. 80, 81, 83, 84) are present. 



As the embryo grows the rounded forms of the parasite in 

 the stomach (which is the chief cavity within the young Melo- 

 phagus) also grow (PI. 13, figs. 82-84). The Crithidia 

 then undergo multiple division, small rosettes (PI. 13, figs. 

 85-88), analogous to pre-flagellate rosettes, being produced. 

 The division clusters may separate, giving rise to small, pear- 

 shaped or ovoid individuals (PI. 13, figs. 89-94), or they may 

 remain as a I'osette (PL 13, fig. 88) for some time. Whether 

 the Crithidia remain as groups or become isolated as oval 

 non-liagellated bodies, they undergo no further development 

 for a considerable period. In fact, when the young Melo- 

 phagus is hatched, a month after extrusion of the pupai-ium, 

 there is still no further differentiation in the parasite. 



Freshly hatched Melophagus do not contain the fully 

 developed flagellates, but the rounded or pear-shaped pre- 

 flagellate forms (PI. 13, figs. 92-94) and rosettes (PI. 13, fig. 

 88) may be present. The parasites appear to lie dormant for 

 a day or two, during which time the young insect does not 

 appear to suck blood. Soon after the first meal of blood is 

 taken, rapid development of the pre-flagellate forms occurs 

 and the adult flagellate, form of the Crithidia is quickly 

 assumed. 



' A plasm odiiini is really a multiniioleate mass of protoplasm 

 formed by fusion of small amoebse. However, the term is sometimes 

 iised, as in describing certain Haplosporidia, for a mi;ltinucleate 

 mass of protoplasm formed by division. 



