11 



In the chapter on natural history by Mr. David E. Lantz there is 

 given a classification of rats as well as the distribution of the genus 

 Mus in America. An interesting and important fact is mentioned 

 that the Biological Survey has no records of the presence of the 

 brown rat in Nevada, Utah, Wyoming, Idaho, and the greater part 

 of Montana. Mr. Lantz also describes the different species in 

 America, and refers to their habits as to breeding, feeding, migra- 

 tions, invasions, and ferocity. The facts presented by him em- 

 phasize the great difficulty of ridding cities of these pests. 



Passed Assistant Surgeon McCoy discusses plague infections in rats 

 and describes the methods of examination. He also describes the 

 gross lesions found in plague rats, gives the bacteriologic diagnosis 

 of rat plague and the cultural characteristics of the plague bacillus 

 on various media. He gives the methods of artificial infefetion of 

 rats with plague, and reviews the recent work of Ledingham in 

 relation to the histology of rat plague. Finally, he presents results 

 of his own investigations to show that the wild rat is not especially 

 susceptible to plague infection, and that a certain percentage of such 

 animals enjoy a natural immunity to plague. 



Doctor Brinckerhoff discusses rat leprosy; states that it is very sim- 

 ilar to human leprosy, and that it is caused by a bacillus which 

 closely resembles the bacillus of Hansen. He describes the patho- 

 logical changes found, and expresses the hope that the disease will 

 receive further earnest study, in order that additional information 

 may throw light on the problems presented by leprosy in man. 



Passed Assistant Surgeon Currie briefly- outlines the bacterial dis- 

 eases of the rat, other than plague and leprosy. He mentions the 

 great utility that would follow the discovery of a rat destroying 

 bacterium, but states that it appears now more than probable that 

 few such natural diseases of rats exist. 



In a chapter on organic diseases of the rat. Doctor McCoy sum- 

 marizes the results of his observations made during examinations of 

 these animals in the Federal laboratory of the service at San Fran- 

 cisco. These observations are of interest, and will assist those 

 engaged in such work to further classify the pathological changes 

 noted as well as differentiate them from plague. 



The ecto parasites of the rat are. classified and described by Mr. 

 Nathan Banks, and he has presented in condensed form information 

 of much practical value upon the subject. 



Dr. Ch. Wardell Stiles discusses the internal parasites of rats and 

 mice in relation to the diseases of man. He regards the rat as a per- 

 manent reservoir for trichinosis, and states that this disease will 

 probably never be eradicated from man until rats and mice, are 

 practically eradicated, and a national campaign directed against 

 trichinosis must take the rat into consideration. 



