CORRIGENDA ET ADDENDA. 605 



features of the new form of microscope are, that the 

 bearings for the compound body, stage, and sub- stage are 

 all fitted, while connected together into the dovetailed 

 slide running from top to bottom of the instrument. The 

 magnet is attached to the under part of the stage, and a 

 gilt iron bar, ledge, or keeper, serves for an object-rest. 

 The sub-stage is constructed of three thin plates having 

 rectangular movements, the top one having a tube attached, 

 into which is fitted the Polariscope, spotted lens, &c., the 

 focussing of which is by a rack placed below. The mirror, 

 being provided with a double-jointed arm, can be used 

 with any amount of obliquity. The stand forms a tripod 

 strengthened by cross bars, the beauty of the chain move- 

 ments (with which all Mr. Ladd's microscopes are furnished) 

 is made apparent by a simple and effective fine adjustment 

 attached to the milled head, thus making the one adjust- 

 ment subsidiary to both purposes. The general appear- 

 ance of the instrument is one of elegance, stability, light- 

 ness, and compactness. 



P. 159.] Mr. Norman writes me: "The beautiful 

 rosette crystals described by Dr. Herapath are best made 

 in the following manner : 



"I make a pretty strong solution of Cinchonidine in 

 Herapath's test-fluid (as described in your work). A little 

 of this is dropped on the centre of a slide and laid down 

 for a time, until the first crystals are observed to be 

 forming near the margin. The slide is now placed upon 

 the stage of the microscope, and the progress of formation 

 of the rosettes closely watched. When these have arrived 

 at a size large enough, and it is deemed necessary to stop 

 their further development, the slide must be quickly 

 transferred to the palm of the hand, the warmth of which 

 will be found sufficient to stop further crystallization. I 

 have found this preferable to holding the slide over the 

 lamp, however carefully it may be done. I may state 

 with Cinchonidine this plan is certain, but with Quinidine 

 impossible." 



P. 184.] The author, in following Robin and Gudden 

 in the investigation of cutaneous diseases, referred to at 

 page 184, gave only their results. He has since in- 



