110 



THE AMERICAN MONTHLY 



[June, 



ute and a half, and repeat this three 

 to five times. Go on with these 

 operations until the diatoms settle 

 for three, four or five minutes, and 

 the result will be that the frustules 

 will be well separated into large and 

 small forms in the different tubes, 

 and experiment will soon indicate 

 what time should be allowed for 

 settling to get them free from 

 broken frustules and particles of 

 debris. The times stated above are 

 purely empirical. They should be 

 determined by experiment, by using 

 the microscope, for each gathering. 



5. Filtered water is pure enough 

 for the operations described above, 

 but to preserve or mount the dia- 

 toms they should be finally washed 

 with distilled water, then placed in 

 a mixture of distilled water and 

 alcohol in equal parts, and kept in 

 small glass-stoppered bottles. 



The ammonia is used to remove 

 floccullent matter, and in some in- 

 stances the effect is very marked. 



It is not advisable to keep cleaned 

 diatoms in bottles with cork stop- 

 pers, for after a while the alcohol 

 becomes discolored by the cork, 

 and the diatoms become dirty in 

 appearance. 



{To he continued.) 



Microscopic Examination of 

 Tissues after the Admin- 

 istration of Mercury.* 



BY S. V. CLEVENGEK, M. D. 



Five years ago it occurred to me 

 that the medicinal workings of 

 mercury could be accounted for by 

 supposing that the finely divided 

 metal underwent no change after it 

 was taken, but passed into the min- 

 ute, tubular structures of the body, 

 and cleared them of morbid accu- 

 mulation. I found no justification 

 for this view in the writings of 



* Read before the Illinois State Microsco- 

 pical Society, Chicago, February 27th, 1880. 



therapeutists, and endeavored to 

 rid myself of the notion, hoping 

 and waiting for the true moduk 

 operandi to be discovered. I read 

 of theories emanating from authori- 

 tative sources quite as puerile as 1 

 then conceived my own hypothesis 

 to be. The greatest objection tp 

 the mechanical theory, seemed to 

 be the fact that the mercury of the 

 salts must undergo reduction in the 

 body to the metallic form, to ac- 

 count for their physiological effects. 

 For the purpose of defeating my 

 own assumptions and forever rid- 

 ding myself of speculation in this 

 direction, I began a series of ex- 

 periments which, though not yet 

 concluded, have confirmed my ori- 

 ginal views. Calomel is reduced 

 to metal, in the duodenmn, by the 

 pancreatic juice and glucose ; cor- 

 rosive sublimate passes into yellow 

 oxide and extremely divided metallic 

 globules in the intestinal fluids, and 

 in alkaline blood ; cyanide of mer- 

 cury is decomposed in the stomach 

 by its hydrochloric acid, and forms 

 the bichloride of mercury, which is 

 then reduced as just mentioned. 

 The iodides, bromides and oxides 

 are similarly broken up, all the 

 mercuric salts acting alike in preci- 

 pitating a more finely divided metal, 

 and the mercurous salts resemble 

 calomel and blue mass ; the effects 

 of all being modified, but not essen-. 

 tially, by the elements combined 

 in the preparation given. The mi- 

 croscope revealed the courses taken 

 by the separate globules through . 

 the intestines, lacteals, veins, arte- 

 ries and lymphatics, and I believe 

 that some valuable results will be 

 obtained in studying histological 

 tissues thus injected before death. 

 Tubular structures, which would 

 escape the scrutiny of the observers 

 with the best appliances and under 

 the highest powers, would be thus 

 rendered apparent. 



