LIFE-HISTORY OP THE PARASITES OF MALARIA. 575 



nature of the nuclear changes during the growth of the 

 zygotes, but it is clear that the parasite acquires a very 

 distinct capsule, and that its substance divides into from eight 

 to twelve meres, which can easily be distinguished without 

 staining. Each mere seems finally to become a spherical 

 blastophore, bearing on its surface a number of filamentous, 

 or rather spindle-shaped blasts, in the manner depicted in 

 fig. 60; at least, it is easy, by rupturing a nearly mature 

 zygote, to expel a number of such bodies. When the zygote 

 finally reaches maturity the blastophores disappear, leaving 

 the capsule packed with thousands of the blasts (and con- 

 taining also some residual fatty globules). 



The capsule now bui-sts spontaneously, and pours the 

 blasts into the body-cavity of the gnat. On drying and 

 staining the blasts are easily seen to be of about 12 to 16 /i 

 in length, with a central nucleus, one or two clear oval areas, 

 and tapering extremities. No definite movements have been 

 observed in these bodies — possibly on account of the reagent 

 (salt solution) which must be used to make them visible in 

 fresh preparations. By some means or other, however, they 

 find their way into remote parts of the host, and finally pierce 

 the capsule of its salivary gland, enter the salivary cells, and 

 lastly the salivary ducts, in all of which situations they can 

 easily be seen with the aid of a strong salt solution. From 

 the salivary ducts they evidently pass through the insect's 

 middle stylet or tongue into the circulation of a fresh verte- 

 brate host, in which it is to be presumed they at once become 

 the amoebulge with which the life-history of the parasites 

 commenced. At all events, numerous experiments, both on 

 birds and on man, have deraoustrated the fact that gnats 

 whose salivary glands contain the blasts are capable of 

 establishing infection by their bites in the appropriate verte- 

 brate hosts. 



It should be noted that this life-history is in no way a 

 hypothetical one. Every fact has been confirmed over and 

 over again by many capable observers. The stages in the 

 vertebrate hosts, first established by Laveran and Golgi, have 



