6 TitE MtcRoscoPE; 



I have not tried it with staining fluids. This I must leaVe to 

 others. M. Poli, however, in the note already referred to, says 

 that objects treated with it, stained green and then mounted in 

 Canada balsam retain their color. Further than that nothing is 

 known about this part of the suDJect. 



The reader will perceive that my experiments have been feW 

 and of little importance. I mention the matter only because I 

 believe the menstruum will prove to be an exceedingly useful onej 

 especially to the amateur, to whom the simplifying of the pro- 

 cess, and the avoidance of the use of absolute alcohol should 

 certainly make it acceptable. The suggestion is nol original 

 with M, Poli, as the oil has been used by others and referred to 

 in print, but has neVer come into general use, as it should. 



I wish Dr Thomas Taylor, of the Department of Agriculture, 

 Dr F. L. James, Prof H. M, Whelpley, Miss M. A. Booth, and 

 other expert preparers of microscopic objects would experiment 

 with the oil, and report their results for the benefit of us that do 

 less in that way than they. I suggest the subject and leave it 

 with the reader, feeling sure that the use of the oil is to be com- 

 mended. 



PROFESSOR KOCH AND HIS DISCO VERIEST 



DR CHARLES HACKS. 



" My hour of consultation is between 12 and 1 o'clock," signed 

 " Koch." This is written on a little square piece of paper fas^ 

 tened by four pins in a gray frame against the wall at the foot 

 of the grand staircase in the entrance of the Imperial Hygienic 

 Institute, in Berlin, and it Was this that four European reporters 

 were studying on the 5th of November, at 9 o'clock in the morn- 

 ing. Alas I what an illusion I Many others have been stopped 

 by that little card, and gone no further. It is not easy, in factj 

 to reach this celebrated saVant. From the porter to the secre-* 

 taries, every one is extremely reserved in that house. It is 

 almost impossible not to have one's card intercepted before it 

 reaches its destination. We had the good fortune, nevertheless, 

 to overcome all obstacles, and by exceptional favor obtained ad- 

 mission. 



Dr Koch Was born December 11, 1843, at Clausthal, where 



I L' Illuatratiun. Of. Scientific American. 



