142 THE AMERICAN MONTHLY [May 
persons suffering from malaria fever, a parasite which is 
always present under these circumstances, and in all prob- 
ability acts as the cause of all malarial phenomena. The 
parasites are varieties of sporozoa which live inside of the 
cell of the individual attacked. The parasite of malarial 
fever occurs in three forms, namely, as that of Tertian 
fever, that of Quartan fever and the parasite of the al- 
ready mentioned Aestivo-Autumnal. A parasite of Ter- 
tian fever is a small Hyaline colorless body which occupies 
but a slight extent of the interior of the cell. When quiet, 
the parasite is round like the corpuscle but if examined 
fresh, it will be seen to have active Ameeboid motion. By 
the terms Tertian and Quartan, we mean as for Tertiana 
fever which occurs every two days and for Quartan every 
three days. We may have a double Tertian or in other 
words, a Quotidian type in which the attack occurs daily. 
The cause of the paroxysm at a stated time is explained 
by the fact that when segmentation occurs in the full 
grown parasite we may look for an attack. The Quotid- 
ian fever is explained by the fact that two sets of par- 
asites operate, one set segmenting say to-day, and the 
other to-morrow. The Quartan parasite which causes an 
attack every third day in its earlier stage of development, 
looks very much like that of Tertian form, for it occurs as 
a small Hyaline Ameeboid body filling a fraction of the 
corpuscle. It soon, however, develops the following dif- 
ferences: first, it develops a sharper outline; second, it is 
more refractive; third, the Amceboid movement is slower; 
fourth, the pigment granules are coarser and more im- 
portant, they lie very quietly around the edge of the par- 
asite; fifth, the corpuscle acts as host and does not in- 
crease in sizeand finally disappears. In the third form of 
infection, the Aestivo-Autumnal, we find small Hyaline 
bodies. They have ringed appearance and are sometimes 
very small. Suddenly this body becomes larger and the 
ring is lost. Then however an Amceboid movement takes 
