1895 THE MICROSCOPE. 87 



It is especially in diphtheria that the anti-toxine meth- 

 od has been extensively applied and its results carefully 

 tabulated. Statistics have shown a reduction of the 

 death-rate from about 40 per cent to 13 per cent in epi- 

 demics of equally widespread prevalence and virulence 

 of type. Of all animals fit for furnishing anti-diphtheritic 

 serum, the one most used is the horse. He is the most 

 easily immunized ; bearing the toxine better than other 

 animals, he is capable of furnishing large quantities of 

 anti-toxic serum at short intervals, and his serum appears 

 comparatively inoffensive to animals and man. The 

 horses employed are carefully examined for evidence of 

 organic disease, especially of the kidneys, and are sub- 

 jected to an injection of mallein to ascertain if they have 

 glanders. Their healthy condition being established, 

 the injections are made into the skin of the neck or back 

 of the shoulders. Having the animal brought up to a 

 certain degree of immunity, the next step is to keep him 

 there, or improve the strength of his serum by large doses 

 of very virulent cultures. Finally, the horse having been 

 found in a satisfactory condition, the blood is withdrawn 

 from the jugular veins, through a sterilized canula, into 

 sterilized vessels and allowed to separate. The resultant 

 serum is then passed through an unglazed porcelain fil- 

 ter and transferred to sterilized bottles for use. 



The Origin of Clays in New Jersey Containing Diatoms. 



By ARTHUR M. EDWARDS, M. D. 



NEWARK, N. J. 



In the course of my perigrinations about New Jersey 

 during the last four years, in searching for geological 

 phenomena, I have observed phenomena which relate to 

 the Bacillariacese. These wide-spread phenomena are 

 known to microscopists alone. The geologists know 



