ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 371 



this method, unless the film be deeply stained and washed very slightly 

 in water. 



New Anaerobic Apparatus.* — A. R. Laing has devised an apparatus 

 which consists of a glass jar (fig. 61) with a constriction near the base, 

 and surmounted with a closely fitting lid. Near the top is a short tube 

 for connection with an exhaust pump. Below the constriction is another 

 opening, through which passes a glass tube kept tight by means of a 

 rubber cork. The upper end of the tube has two arms, one having 

 a reservoir for caustic potash, the other leading to the hydrogen supply. 

 Both arms are furnished with stop-cocks. 



To work the apparatus, a sufficiency of pyrogallic acid is first put 

 into the reservoir below the constriction ; upon the latter is placed a 

 perforated porcelain plate, on which the cultivation vessels rest. The 

 glass lid is smeared with vaselin and pressed firmly down, and the gap 

 between the lid and the jar filled with paraffin soap. The air is then 

 exhausted and the apparatus filled with hydrogen, this process being 

 repeated six times to ensure a complete hydrogen atmosphere. A little 

 of the hydrogen is removed by means of the exhaust, in order to have 

 slight negative pressure within the vessel. Potash solution is then 

 run in. 



W.J.S. — Collecting and preparing Diatoms. English Mechanic, lxxix. (1904) p. 84. 



(2) Preparing Objects. 



Preparing Small Dried Insects for Microscopical Examination.! 

 G. Enderlein claims good results from the following treatment of such 

 dried material. The insect is placed carefully in a mixture of 1 part 

 moderately strong caustic potash solution and 8 to 10 parts water. If 

 winged, these appendages are best first removed. If, however, the 

 insect is a very delicate one, the wings may be left on, and a weaker 

 solution of the alkali employed. According to the size and delicacy of 

 the object, it remains in this solution from 10 minutes to 1 hour, until 

 indeed the natural form has been regained. It is then placed in water, 

 being carefully watched the while, lest undue swelling take place. The 

 larger air-bubbles are now removed with a fine brush, and the object 

 again placed for a short time in dilute caustic potash, transferred to 

 water, and then taken gradually into 96 p.c. alcohol, when the remaining 

 air-bubbles are removed as before. In 96 p.c. alcohol it can be kept. 

 If a microscopic preparation is desired, as much as possible of the body 

 contents are removed by pressure with a fine brush. The object is 

 then arranged suitably, passed through absolute alcohol and cedar oil, 

 and mounted in Canada balsam. If one is dealing with very thin 

 chitinous structures, e.g. delicate abdominal walls, it is well to mount the 

 specimen in glycerin directly after water. 



The author makes permanent glycerin preparations by fixing the 

 cover-glass, on which no glycerin should be allowed to flow over, to the 

 slide by means of a ring of wax. This being done, Canada balsam or 



* Lancet, i. (1904) p. 515 (1 fig.). 

 1 f Zool. Anz., xxvii. (1904) pp 479-80. 



