1892.] MICKOSCOPICAL JOUENAL. 73 



ing i8 words per line. Henry C. Hyde showed an interesting series 

 of chemical crystals, and a volume of photographs in 59 large plates of 

 MoUer's wonderful collection of diatoms. The collection embraces 

 upwards of 4,000 named varieties and is valued at $10,000. J. (7. 

 Clark showed various specimens of crystals of gold and silver, both 

 native and produced bv the galvanic current. L. M. King had 

 under his microscope many forms of diatoms in sitic^ while S. E. 

 Tavlor had a fine assortment of arranged diatom slides from the lab- 

 oratorv of Thum, Leipsic. George Otis Mitchell confined his attention 

 to insect eggs and the apparatus for placing them in position, including 

 the wonderful saw by which the fly inserts its eggs under the cuticle 

 of various leaves. E. W. Runyon had a well-assorted list of objects 

 shown by dark-field illumination, and several objects from the animal 

 kingdom under polarized light. 



MEDICAL MICROSCOPY. 



The Klebs-Loeffler Bacillus and Associated Forms. — Our 



bacteriologists are doing splendid work in the study of the micro- 

 organisms of diphtheria. A decade of such work (perhaps less) will 

 place our knowledge of these malignant plants on a solid basis. 



Meanwhile, the fact remains that we have as yet no certain test 

 which can be applied by the ordinary practitioner or microscopist to 

 distinguish Loeffler's bacillus diphtherite from the so-called pseudo- 

 diphtheritic bacilli which are associated with non-malignant angina. 

 Even if the experts were thoroughly agreed about points of differen- 

 tiation — and thev are not — the necessary tests occupy several days, and 

 the most conclusive is inoculation. 



The most urgent question is whether the pseudo- diphtheritic bacillus 

 may not be an attenuate form of the true bacillus diphtherice, and 

 capable of developing malignant powers under circumstances favorable 

 to itself. If this question be answered in the affirmative, then the ques- 

 tion comes, Does the case of follicular tonsilitis require the same careful 

 isolation as a case of true diphtheria.' — F. Blanchard^ JSI.D. 



The Water Supply of Washington. — During the past three 

 months our hydrant water has certainly presented an alarming appear- 

 ance. Doubtless many physicians have been asked by their patrons 

 whether the water is really as sick as it looks. Now, it is not as 

 pathogenically bad as it looks ; but it may be bad, and the family phy- 

 sician will do well to give a guarded answer to such questions. 



The chief cause of its turbid, milky appearance is clay, in the form 

 of almost impalpable powder. The frost disintegrates the clayey 

 banks of the Potomac ; the heavy autumn rains wash the fine particles 

 into the river ; and, as the specific gravity of clay is low, no ordinary 

 process of settling suffices to separate it from the water. Filtration 

 through the excellent filters now in the market accomplishes this on a 

 small scale ; and probably filtration through large beds of sand would 

 do the same for the whole mass of water supplied to the city. 



But clay alone is not a very dangerous addition to our diet. The 

 live question is, Does the clay bring along witli it other matter which 

 is really morbific' We should naturally expect that it might, and 



