188 



which the hibernating material is only a very inconspicuous fraction, 

 does not seem to influence or to have influenced the malaria curve in 

 any way. From our present knowledge of the malaria-plasmodia and the Ano- 

 phelines we are able to understand a malaria curve with its climax in August, 

 such as is the case with Italy, and a curve with two climaxes, one lower in May, 

 and a much greater in August — September. 



Curves of this kind are in fact pointed out for several epidemics north of the 

 Alps (Ditmarshen 1842 bis 63; Doose in Hirsch 1881 p. 175); Wilhelmshafen ( Wenzel 

 1870 p. 28) but they are not the rule. The very curve which in my opinion we 

 are not able to understand, a curve with only one vertex lying in May — June, is 

 that which seems to be the rule for all epidemics north of the Alps. It is only in- 

 telligible on two assumptions, which in my opinion are both equally improbable. 

 The one is that the Anophelines of the summer have sucked parasites into the 

 intestine, have formed their oocystes and hibernated with them on the walls of the 

 intestines and. then in spring infected man. This is improbable according to all 

 more thorough investigations, which seem to show that the parasites hibernate 

 in man and not in mosquitoes. The other assumption is that the summer- 



broods really give malaria to man but that it is latently present till May; man 

 lives with the parasites during winter, but the outbreak does not take place before 

 May. This indeed is by no means in disaccordance with the nature of malaria; it 

 is a well-known fact that a very long time may pass before a malaria attack pro- 

 duced either by external or internal, physic or psychic conditions, really breaks out. 

 See e. g. the report by Kirschuaum (1917 p. 1405) on the malaria outbreak in 

 North West Russia in February in ice and snow. Quite a similar result is arrived 

 at by Werner (1917 p. 1375). Yet also this supposition must be regarded as an 

 absurdity. P'or we are quite unable to understand why the malaria transferred by 

 hibernating mosquitoes in April — May invariably should be able to influence the 

 curve after the course of a few weeks and produce the high-lying vertex in the 

 course of only a few weeks, whereas that malaria which is transferred in the sum- 

 mer months does not in any way influence the curve before eight months later; if 

 the summer-generations had transferred malaria we should have expected a second 

 vertex on the curve a few weeks later. See also Martini (1920j p. 69). 



Zieman has pointed out that if there was any possibility that the Anophelines 

 infected themselves, that the parasites from the mother mosquito were transferred 

 to the eggs and from them through larvae and pupse into a new generation, the 

 malaria curves would be more intelligible. As well known, both Schaudin and 

 Doflein (1916 p. 933) have reckoned with this possibility. Moreover the supposition 

 is allowable because others of our great parasitical diseases, e. g. Texas fever, really 

 are spread in this manner. As far as I can see here is really a point where more 

 thorough investigations are desirable. But even if it should be shown that the Ano- 

 phelines are able to infect themselves this would not help us in our case. For north 

 of the Alps we have really only one malaria carrier i. e. A. maculipennis, and even 



