1030 RECORD OF CURRENT RESEARCHES RELATING TO 



to be recommended), the wings are transferred to the slide direct from 

 the water in which they are washed, then allowed to dry (sometimes 

 hastened by holding the slide over the flame of a lamp) ; and, when 

 quite dry, a drop of glycerine is to be added, and the cover at once put 

 on. When the glycerine has penetrated around the edges so as to 

 completely saturate portions of the wing, the scales at once become 

 transparent, and the structure is clearly apparent. 



By holding the slide over the lamp till ebullition takes place, the 

 glycerine will be found to replace the air under the concave portions 

 of the wings, without any injury to the structure ; and even in those 

 refractory cases when the glycerine has been allowed to boil for a 

 considerable length of time, no injury was found to be done to the 

 wing-membrane. 



Microscopical Investigation of Wood. — The Vienna Academy 

 propose as the subject for the Baumgartner prize of 1000 florins, 

 " The microscopical investigation of the wood of living and fossil 

 plants." By such investigation, and the comparison of all known 

 recent and fossil woods, it is desired to ascertain characters whereby 

 it will be possible to determine the genus and species with certainty 

 from microscopical sections. Papers must be sent in before Decem- 

 ber 31st, 1882, and the prize will be awarded at the anniversary 

 meeting in 1883. 



Permanent Preparations of Plasmodium.* — Two methods are 

 already known for making permanent preparations of the motile or 

 naked protoplasmic stage of the Myxomycetes ; the older one being to 

 dry the extended plasmodium, and the newer, to harden it with osmic 

 acid. Both these methods are defective, for osmic acid changes the 

 colour of the protoplasm, and drying causes it to shrink as well as to 

 change colour. 



Mr. S. H. Gage gives the following as a simple and efficient 

 method of extension and preservation : Small pieces of the rotten 

 wood, on which the plasmodium is found, should be placed on 

 moistened microscope-slides, with some of the plasmodium touching 

 the slides. These should be on a piece of window or plate glass, and 

 over the whole should be placed a bell-jar, or other cover, to prevent 

 evaporation. After an hour or more, the glass on which the slides 

 rest should be lifted up to see whether the plasmodium has crawled 

 out upon any of the slides. If any of the slides are satisfactory, lift 

 off the bell-jar, and remove the pieces of wood from the slide, the 

 Plasmodium remaining. The slide should then be put very gently 

 into a mixture of equal parts of a saturated aqueous solution of picric 

 acid and 95 per cent, alcohol ; it should be removed in fifteen or twenty 

 minutes, and placed, for about the same length of time, in 95 per 

 cent, alcohol ; it may then be mounted in Canada balsam in the 

 usual way, but without previous clearing. The picric acid stiffens the 

 protoplasm almost instantly, but does not shrink it ; the alcohol 

 removes the water, and allows of Canada balsam mounting. 



* 'Am. Mon. Micr. Journ.,' i. (1880) pp. 173-4. (Paper read before the 

 Sub-section of Microscopy of the Am. Assoc. Adv. Sci.) 



