242 THE PROTOZOA 



In full grown schizonts we find the chromatin in separate aggregations through- 

 out the parasite while the pigment is clumped. In gametes the pigment is 

 scattered and the chromatin is in a single mass. 



If many young ring forms are present during pyrexia it is probable that the 

 infection is E.A. 



In parthenogenesis, as observed in P. vivax, the nonsexual forms and the males 

 die off leaving only the female forms. The nucleus divides into a dense and light 

 portion. The latter degenerates and the former goes on to merozoite formation. 



This is Schaudinn's explanation of relapses. Another explanation of latent 

 malaria is by conjugation of two ring forms. 



In the diagnosis of malaria one should always examine both a fresh 

 specimen and a stained one, as each method gives valuable information 

 in differentiating species. When time will not permit the examination 

 by both methods, always use the smear stained by Wright's stain, as 

 the small peripherally situated rings of aestivo-autumnal fever may 

 escape notice in a fresh specimen. 



For the cultivation of malarial parasites (Bass) the blood in 10 to 20 c.c. quan- 

 tities is taken from the patient's vein and received in a centrifuge tube which con- 

 tains i/io c.c. of 50% glucose solution. A glass rod, or piece of tubing, extending 

 to the bottom of the centrifuge tube is used to defibrinate the blood. After centrif u- 

 galizing there should be at least i inch of serum above the cell sediment. The 

 parasites develop in the upper cell layer about 1/50 to 1/20 inch from the top. All 

 of the parasites contained in deeper lying red cells die. To observe the development, 

 red cells from this upper i/20-inch portion are drawn up with a capillary bulb pipette. 



Should the cultivation of more than one generation be desired, the leukocyte 

 upper layer must be carefully pipetted off, as the leukocytes immediately destroy 

 the merozoites. Only the parasites within red cells escape phagocytosis. Sexual 

 parasites are much more resistant, and the authors think they observed partheno- 

 genesis. The temperature should be from 40 to 41 C. and strict anaerobic condi- 

 tions observed, ^stivo-autumnal organisms are more resistant than benign tertian 

 ones. Dextrose seems to be an essential for the development of the parasites. 



Bass considers that P. vivax has a flat amoeboid like structure which enables it 

 to squeeze through the brain capillaries while adult schizonts of P. falciparum have 

 a solid oval form which causes them to be caught in the capillaries. 



Belonging like the malarial parasite to the Haemosporidia we have a group of 

 parasites known as the PIROPLASMS. The correct name for these parasites is Babesia 

 but they are better known under the name Piroplasma. They are minute organisms, 

 usually pear or rod shape, which invade the red corpuscles. They produce no 

 pigment but destroy the corpuscle and set free the Hb. which is excreted in enor- 

 mous amounts by the kidneys. It is this which gives the name redwater to the better 

 known Texas fever of cattle. Organisms of this kind have been thought of in con- 

 nection with blackwater fever of man. Seidelin has claimed that a parasite of 

 similar nature, P ar a plasma flavigemim, was the cause of yellow fever. 



At one time spotted fever of the Rocky Mountains was supposed to be due to 

 a parasite named Babesia hominis. 



