4o8 RESEARCH IN PROTOZOOLOGY 



done in cases of human malaria where conditions can be controlled 

 and where there is a sufficient amount of blood to be sure of the 

 results. On account of the large experimental error due to the small 

 amount of blood obtainable, the data with regard to quantitative 

 work on the canary blood have not been published. 



In the one human case followed, it was shown that the blood 

 sugar increased during the paroxysms of chill, etc. This suggests 

 that at least twenty-five cases should be accurately followed, the 

 blood sugar being determined before inoculation with malaria, 

 and determinations being made between and during paroxysms of 

 sporulation. In most cases where malaria is used as an agent for 

 the treatment for disease, a heavy infection is wanted, so it would 

 do no harm to administer glucose during the period of sporulation 

 of the parasite if that period can be determined. It will do no good 

 to administer it at any other time. 



II. CHANGES OF ENVIRONMENT 



That infections of canaries with PlasiJiodium catJicmerium are 

 characterized by a definite periodicity in the reproductive activity 

 of the parasite was shown by L. G. Taliaferro (1925). She 

 showed that pronounced periods of reproduction occur at twenty- 

 four-hour intervals, and her observations in this connection have 

 been confirmed by Drensky and Hegner (1926) and Hartman 

 (1927). These infections of birds, therefore, offer suitable ma- 

 terial for the study of this interesting and important phenomenon 

 which is such an outstanding feature of certain malaria infections 

 of the human. 



A common explanation of the above-mentioned periodicity in 

 human malaria is that each species of parasite in these infections 

 has a definite length of its asexual cycle of development. Since 

 such is the case and since all parasites injected into the vertebrate 

 host by the mosquito are in the same stage of development 

 (namely, the sporozoite), it is assumed that they undergo further 

 development synchronously and reach maturity and enter upon 

 the process of schizogony at approximately the same time. The 

 continuation of such synchronism results in the subsequent repe- 

 tition of these periods of reproduction at regular intervals. Based 

 upon such an explanation, the idea has become very prevalent 

 that the basis for the phenomenon of periodicity in malaria is a 

 matter which is firmly fixed in the inherent make-up of the causa- 



