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THE AMERICAN NATURALIST [Vol. XLII 



indicated, no modification or adaptation in the process of repro- 

 duction. But in the infection of the ova with a resting stage is 

 involved a selection both of the definite organ and of the cell 

 which becomes infected. Further, the parasite must assume 

 a resting condition adapted to undergo successfully the changes 

 indicated in the development of the adult insect from the eggs 

 and sometime in the latter process must reach the suitable loca- 

 tion. In the case of the fly such a location will be the alimentary 

 canal of the insect, while in the tick which is to transmit the 

 disease-producing organisms the suitable location will be rather 

 the salivary glands, as suggested by the observations of Chris- 

 tophers. In any event the interrelations arc evidently extremely 

 complicated. The infection of the fetus by tissue-penel ral ing 

 protozoa is purely incidental; the infection of the ova and 

 through them of the second generation is a complicated bio- 

 logical process, involving essential modification in the life-history 

 of the parasite and important morphological adaptations to new 

 conditions of life. 



A Society for the Destruction of Vermin. — Recent demonstrations 

 as to the agency of mosquitoes, flies, bedbugs, rats and other 

 household pests in transmitting serious diseases has taken such 

 active hold on the British mind that there has been organized in 

 London a Society for the Destruction of Vermin. It is incor- 

 porated under the Board of Trade regulations as a public associa- 

 tion not formed for the object of making profit. The work the 

 society has set itself to do is: (1) Collect information from all 

 sources on the distribution and life-history of vermin. It will 

 pay special attention to the part played by vermin in disease 

 causation. (2) Disseminate as widely as possible the acquired 

 knowledge by means of the general press, and also by special 

 reports, leaflets and lectures. It will endeavor to make known 

 to the public the dangers connected with each kind of vermin, 

 the necessity for exterminating certain species, and the best 

 means of destruction. (3) Carry out experiments in the field, 

 test any. promising measures suggested for the destruction of 

 vermin, and, if funds permit, distribute gratuitously, to such 

 persons as are unable to afford the expense, the necessary sub- 



