1897.] MICROSCOPICAL JOURNAL. 295 



The accurate reproduction of these various vital pro- 

 cesses of cell life, he thinks, will be of g-reat assistance in 

 revealing- the exact condition of the blood, and help us to 

 g^et one step nearer the ultimate processes of life. Dr. 

 Watkins does not hesitate to say that various cells now 

 known by different names will be found to be only transi- 

 tion forms of the leucocyte. The amoeboid motion of the 

 leucocyte continues sometimes for fully twenty-four hours 

 after the blood is placed on the slide of the microscope. 



There is another field of usefulness in which the micro- 

 motoscope may prove of service, and that is in the study 

 of the life of microbes in stale urine and other fermenting- 

 fluids, and in the study of the motile efforts of all micros- 

 copic g-erms and bacilli. 



To secure an appearance of continuous motion, these 

 pictures must be taken in rapid succession, allowing- an 

 exposureof from one fiftieth to one twenty-fifth of a second; 

 and to complete a full cycle of motion, as in the expansion 

 and contraction of a leucocyte, requires from eig-ht hun- 

 dred to fifteen hundred successive pictures. The time 

 between the first and the second photographs is two minu- 

 tes; the others are fifteen minutes apart; allowing- an 

 exposure of from one to two seconds. The impression 

 made by their rapid passag-e before the eye when placed 

 in a vitascope gives the sensation of continuous motion. 



MICROSCOPICAL MANIPULATION. 



Separation of Diatoms, etc.,- from Sand. — For this 

 purpose we use certain liquids of high specihc g-ravit}^, 

 such as are used in minerological operations, and we 

 commend the following : 



Brown's liquid: Methylene iodine, which has a specific 

 gravity of 3.3. By adding- iodoform to this, this figure is 

 raised to 3.45, while iodine increases it to 3.65. 



Klein's liquid : Potassium-boro-wolframin, the specific 

 g-ravity of which is 3.28. 



Rohrbach's liquid: Barium-mercury iodine, s. g-., 3.58. 

 Toulet's liquid: Sodium-mercury-iodide, s. g-., 3.19. 



