ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 741 



Before tte benzole has quite evaporated, fill up the cell with balsam 

 and benzole until it appears heaped up above the top of the cell. 



The slide should now be put on one side, covered with something, 

 such as a wine-glass or chip-box, to keep off the dust until the benzole 

 has evaporated, which will leave the balsam nearly hard in the cell. It 

 will however be found that, even with care, some dust will have settled 

 upon the surface of the balsam. This can be removed by a camel- 

 hair brush dipped in benzole, and drawn across the surface. If this 

 surface is still higher than the cell, the slide is now ready for the last 

 process, and only needs a cover-glass, which should be warmed and 

 pressed upon the surface, and held down by a spring clip until the 

 existing balsam has become hard, when it can be cleaned off, and the 

 slide subjected to the usual process of ringing. 



Styrax and Liquidambar as Substitutes for Canada Balsam.* — 

 Dr. H. Van Heurck, desiring to obtain a fluid of high refractive 

 index which would not be open to the inconveniences of monobromide 

 of naphthaline as regards the diflBculty of sealing up and the dis- 

 agreeable odour, found that styrax from Liquidambar styraciflora and 

 liquidambar from L. orientalis were excellent media for the purpose, 

 and much less alterable than Canada balsam. Styrax is supplied by 

 Gehe and Co., of Dresden. It contains a granular substance, which 

 is got rid of by dissolving it in chloroform and filtering the solution, 

 which is used for mounting. Liquidambar is preferable as being very 

 pale yellow instead of a brownish yellow, but it does not appear to 

 be obtainable from European druggists. 



The index of refraction is not given. Amphipleiira pellucida is 

 said to show the striae in a " perfect manner," and the author " be- 

 lieves that the use of the above products will rapidly spread, and by 

 reason of their great advantages will completely supplant Canada 

 balsam." 



Practical Processes in Vegetable Histology. f — L. Olivier writes 

 as follows : — 



In studying the structure of a living organism, it is not suffi- 

 cient to examine under the Microscope the form and relations of its 

 elements. We must, in addition, determine the chemical nature of 

 each. In this physiology is as much concerned as general anatomy, 

 physiological functions being the resultant not merely of the mole- 

 cular composition but also of the arrangement of the organic struc- 

 tures. 



The endeavour has therefore been to find for histology reagents 

 capable of discovering in the interior of the cells the presence of the 

 analysed substances. 



Two methods have been adopted. The older and more general 

 consists in examining, under the Microscope, different preparations of 

 the same organ, before and after the successive action of certain 



* Bull. Soc. Belg. Micr., ix. (1883) pp. 134-6. 



t Kev. Bci. Nat., i. (1882) pp. 436-54 ; ii. (1882) pp. 71-91. We have been 

 unable to verify the footnotes so as to print them in the form usual in this 

 Journal, and they are therefore given for the most part as in the original. — Ed. 



