250 HUXLEY, OX THE MOUTH OF THE SCORPION. 



hot, through blotting-paper, may be poured when cold into the 

 tube on removal of the stopples, which are to be replaced ; and 

 when the upper piece e is rotated from left to right, a 

 resplendent coloration is exhibited, following the right-handed 

 prismatic series, in the order of violet, red, orange, yellow, 

 green, blue, indigo, indicative of cane sugar. Then, for the 

 development of the order of coloration indicative of grape or 

 uncrystallizable sugar, proceed as follows : — empty the syrup 

 from the tube into a phial, add two or three drachms of 

 hydrochloric acid (one drachm of acid to nine drachms of 

 syrup), and place aside for twelve hours, or thoughout the 

 night. In the morning replace the acidified solution into the 

 tube a, as before, and note the order of coloration, which, 

 the cane, now being converted into grape-sugar, will, upon 

 the rotation of the analyser or upper stopple e in the same 

 direction as before (from left to right), present the reverse 

 series of colours, or violet, indigo, blue, green, &c, &c. Of 

 course, for practical quantitative or per-centage estimation, 

 regard must be had to exact measures, to which we do not 

 now refer. 



The b eye-piece, selected as a measure for the calibre of 

 the tube or body a, having been removed for the adaptation 

 of the stopples, may at any time be replaced, and, instead 

 of the Nicol's prism, be surmounted with a prism of uncut 

 Iceland spar, or rather by a special double-image prism, 

 for the magnified exhibition of the phenomena of simul- 

 taneous complementary coloration, the syrup being used as 

 before. 



Sufficient may have already been advanced to awaken 

 interest and to induce investigation of the brilliant phenomena 

 of saccharine polarization; and at the same time a clearer con- 

 ception will have been obtained of the manipulation required 

 for the purpose of subjecting diabetic urine to the polariscopc, 

 involving a process probably a little more complex than is 

 usually considered of concentration, clarification, &c. 



On the Sructure of the Mouth and Pharynx of the 

 Scorpion. By Thomas Henry Huxley, F.K.S., Pro- 

 fessor of Natural History, Government School of Mines. 



Although the scorpion has been made the subject of 

 repeated investigations by some of the best minute anatomists 



