M. \L.\U1.\L PARASITOLOGY 509 



dwarfed. It never attains the size of the tertian form. All the steps 

 leading to completed segmentation are seen in the peripheral blood. 



The gametes are not well known. Cases of quartan are relatively rare. 



General Observations. It should be remembered that there 'i> no 

 quotidian form in this country. Quotidian paroxysms are either a double 

 tertian or a triple quartan infection. 



It is also interesting to note that the fever curve Incomes atypical 

 even in those cases in which no quinine has been given. The excur- 

 sions will be less, but the temperature will stay up longer and drop 

 more gradually; or there may be two consecutive paroxysms usually 

 varying in intensity. The parasitic forms in the blood will vary accord- 

 ingly- 



FIG. 154 



24 27 



Quartan type : 22 to 24. young forms ; 25 to 26, tendency to band formation ; 27 to 29, segmenta- 

 tion. (All forms drawn from stained smears.) 



The relationship between segmentation and paroxysm is always 

 noted in tertian cases, and it is reasonable to suppose that the occurrence 

 of the paroxysm is referable entirely to the liberation of toxic substances 

 resulting from metabolic activity of the parasite within the corpuscle. 

 That there should be a toxic product seems highly probable, and its 

 amount must be considerable in heavy infections. Cases showing an 

 infection of 1 to 5 per cent, of all corpuscles are not infrequent; the 

 destruction of from 50,000 to 200,000 or more corpuscles per cubic 

 millimetre of blood leads to the rapid deglobularization of the blood; 

 hence the deficiency in numbers; add to this the effects of the meta- 

 bolic products, and little is left to the imagination to explain the 

 pronounced anremia. Furthermore, the corpuscular remnants will be 

 largely carried to the spleen; hence its hyperplastic condition and 

 pigmentation. 



Malarial parasites can always readily be found in recent primary 

 infections, and it is usually only in old cases that the search becomes 

 difficult; one is, however, generally rewarded by finding them if one 

 looks long enough for them. 



A helpful sign is the finding of pigment in mononuclear leukocytes, 

 which are seen about the time of a chill, or to the period symptom- 

 atically corresponding to it. 



Free pigment cannot be used as a means of diagnosis, as it may be 

 impossible to tell it from dirt or dust. 



A small dose of quinine may drive all parasites of the monogony out of 

 the peripheral circulation; at all events, the finding of them becomes, in 

 the absence of gametocytes, a matter of time and experience, especially 

 also as they may be much altered in appearance. 



Immunity from malaria appears to exist as natural and acquired 

 immunity. Whether the usual assertion that contraction of disease 

 by pyogenic micro-organisms depends upon a lowering of the resist- 



