22-26 Journal of Applied Microscopy 



To study the pits and tubes of the lateral line, the fish is mounted as above 

 described and the microscope is so arranged that direct sunlight, or a strong 

 artificial light, will illuminate the part on which the objective is focussed. The 

 circulation of the blood in the capillaries at the bottom of the pits and in the skin 

 overlaying the scales is easily seen with a half-inch objective. 



The length of time during which a fish will continue to live and exhibit a 

 vigorous circulation when anesthetized with chloretone and mounted for study in 

 this simple manner, depends upon its vitality and the strength of the anesthetic. 

 The proportions of water and chloretone solution suggested above give a solu- 

 tion of minimum strength and it may need to be supplemented occasionally with 

 a drop of one per cent, chloretone placed over the gill-slit so that it will run down 

 over the gill-filaments. This should be done whenever the least motion of the 

 fish is noticed as it lies on the glass plate. A goldfish about two and three- 

 quarters inches long, treated in this way, was studied for over two hours and 

 the circulation continued to be good up to the time it was returned to the 

 aquarium, where it revived. Amceboid movement of the white blood corpuscles 

 and the movement of the granules in the corpuscles was clearly seen near the 

 close of the period of observation. 



Repeated use of this anesthetic at frequent intervals is not usually fatal to 

 goldfish. For example, ten fish were anesthetized in one tray, then distributed 

 to a class whose members made careful drawings, consuming about forty-five 

 minutes, after this the fish were returned to clear water for fifty minutes, then 

 again anesthetized for the same length of time, and all revived within a few 

 hours after being placed in clear water. Their recovery from the anesthetic 

 seems to be hastened by artificial respiration, which is easily accomplished by in- 

 jecting several pipettesful of clear water into the mouth so that it escapes through 

 the gill-clefts, or by repeatedly lifting the operculum with a blunt needle while 

 the fish is loosely held under water. A. H. Cole. 



University of Chicago. 



The History of the Microtome. 



II. THE EARLIEST TYPES— Continued. 



The third initial form of microtome was that devised by Rivet, a French 

 botanist, which was described in the Annales dcs Sciences Naturelles. In 

 Rivet's microtome the feeding of the object was accomplished by shoving 

 it up an inclined plane and not by means of a screw, a principle which 

 is preserved in the Thoma-Jung, or so-called Heidelberg microtome, which 

 is still so much used. Rivet's instrument was made of wood and proved, for 

 botanical purposes, a useful instrument. It was made by Ve'rick, the world 

 known manufacturer of microscopes in Paris. I have never seen one of these 

 instruments. It was, however, copied in Germany, with the improvement that it 

 was made of brass instead of wood, permitting, of course, a very much more 

 exact construction. 



In 1870 Alexander Brandt, who afterwards became a distinguished zoologist, 



