1900] MICROSCOPICAL JOURJNAL. 133 



grain of sand. The eyesight of Melicerta, with its verte- 

 brate retina of rods and cones, is so powerful that it often 

 tries to look at the observer through the other end of his 

 (the observer's own) microscope, and, no doubt, succeeds. 

 A wonderful creature is Melicerta, and, in order to ob- 

 serve all these and other marvellous habits, a good mi- 

 croscope and a little imagination only are required, such 

 as Dr. Weir seems to possess in so high a degree." 



Extracting Air. — The "Optician," says : — One often 

 finds, after killing and hardening any small animal, that 

 some part of it, commonly the intestine, contains air-bub- 

 bles. Also, in decalcifying small calcareous animals with 

 acids, especially when one hurries the process, bubbles of 

 carbon dioxide are not infrequently formed. At all events, 

 whatever the origin of the bubbles, their presence is ad- 

 verse to obtaining perfect sections and series. Such bub- 

 bles of gas can be readily removed by the following pro- 

 cess, due to Professor E. W. Berger, of the Johns Hop- 

 kins University. It is well-known that water contains a 

 considerable quantity of air and some other gases in so- 

 lution, and that these can be removed by boiling the water. 

 Boil therefore, for a short time, several hundred cc. of 

 water, and while this is still quite hot pour it into a bot- 

 tle with a tightly fitting stopper,leaving little or no air be- 

 tween the water and the stopper. When the water has be- 

 come cooled to a lukewarm temperature, place the objects 

 in question into the water and cork the bottle tightly as 

 before. After several hours (two or three to twenty-four 

 hours) the water will have absorbed all the gas, and the 

 object will have settled to the bottom. Should the object 

 still contain gas, repeat the operation. Should one fear 

 that the object may suffer injury, normal salt solution, or 

 alcohol, might be suggested. Unfortunately, however, 

 alcohol contains but little gas in solution. 



New Cambridge Rocking Microtome. — The Cambridge 

 Scientific Company have recently brought out a new and 



