364 POPULAR SCIENCE MONTHLY. 



at the present time. The important point is that the result of the seg- 

 mentation of the adult parasites contained in the red corpuscles is the 

 formation of a large number of spore-like bodies, which are set free by 

 the disintegration of the remains of the blood corpuscles and which con- 

 stitute a new brood of reproductive elements, which in their turn invade 

 healthy blood corpuscles and effect their destruction. This cycle of de- 

 velopment, without doubt, accounts for the periodicity of the charac- 

 teristic febrile paroxysms; and, as stated, the different varieties complete 

 their cycle of development in different periods of time, thus accounting 

 for the recurrence of the paroxysms at intervals of forty-eight hours, in 

 one type of fever and of three days in another type. When a daily 

 paroxysm occurs, this is believed to be due to the alternate development 

 of two groups of parasites of the tertian variety, as it has not been pos- 

 sible to distinguish the parasite found in the blood of persons suffering 

 from a quotidian form of intermittent fever from that of the tertian 

 form. Very often, also, the daily paroxysm occurs on succeeding days 

 at a different hour, while the paroxysm every alternate day is at the 

 same hour, a fact which sustains the view that we have to deal, in such 

 cases, with two broods of the tertian parasite which mature on alternate 

 days. In other cases there may be two distinct paroxysms on the same 

 day, and none on the following day, indicating the presence of two 

 broods of tertian parasites maturing at different hours every second day. 



Manson, in his work on tropical diseases, recently published, ac- 

 counts for the febrile paroxysm as follows: 



"In all malarial attacks this periodicity tends to become, and in most 

 attacks actually is, quotidian, tertian, or quartan in type. If we study 

 the parasites associated with these various types we find that they, too, 

 as has been fully described already, have a corresponding periodicity. We 

 have also seen that the commencement of the fever in each case cor- 

 responds with the breaking up of the sporulating form of the parasite 

 concerned. This last is an important point; for, doubtless, when this 

 breaking up takes place, besides the pigment set free, other residual mat- 

 ters — not so striking optically, it is true, as the pigment, but none the 

 less real — probably are liberated; a haemoglobin solvent, for example, as 

 I have suggested. Whether it be this haemoglobin solvent, or whether 

 it be some other substance, which is the pyrogenetic agent, I believe that 

 some toxin, hitherto enclosed in the body of the parasite, or in the in- 

 fected corpuscle, escapes into the blood at the moment of sporulation. 



"The periodicity of the clinical phenomena is accounted for by the 

 periodicity of the parasite. How are we to account for the periodicity 

 of the parasite? It is true that it has a life of twenty-four hours, or of 

 a multiple of twenty-four hours; but why should the individual parasites 

 of the countless swarm all conspire to mature at or about the same time? 

 That they do so — not perhaps exactly at the same moment, but within a 

 very short time of each other — is a fact, and it is one which can be easily 

 demonstrated. If we wish to see the sporulating forms of the Plas- 

 modium in a pure intermittent, it is practically useless to look for them 

 in the blood during the latter stages of fever, or during the interval, or 



