ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 637 



water, and finally preserved in successive grades of alcohol. A 

 weak solution of iodine in alcohol and sea- water also gives beau- 

 tiful results, but is less certain in its action. For staining he 

 used Grenacher's alum-carmine, borax-carmine, picro-carmine, and 

 Kleinenberg's hasmatoxylin. Much the best results are obtained by 

 the use of alum-carmine, but it must be used as quickly as possible, 

 since the gelatinous tissue of the mesoderm is apt to shrink if the 

 object be left too long in aqueous fluid. The tissues were decalcified 

 with very weak nitric or hydrochloric acid in 90 per cent, alcohol. 

 For maceration, the Hertwigs' well-known mixture of osmic and 

 acetic acid gives good results. 



Semper's Method of making Dried Preparations.* — B. Sharp 



redescribes this process.f 



After hardening in chromic acid solution (^-1 per cent.) and being 

 repeatedly washed, the object is placed in alcohol, 30-40, 60-70, and 

 90-95 per cent, successively, and finally in absolute alcohol. 



This stage of absolute alcohol is the most critical part of the 

 whole process. Absolutely every particle of the water must be removed, 

 and the secret of the whole process depends on this one point. If 

 any water be left in the tissue, it will become spotted and eventually 

 sjioil. After all the water has been withdrawn by the absolute 

 alcohol, by remaining in it for three days to a week, the object is 

 placed in tiirpentine, the best that can be procured. In this it is 

 allowed to remain until it becomes thoroughly saturated : with large 

 objects it is best to change the turpentine once. Two or three days 

 are required for this stage. When saturated, the object is quite stiff, 

 and when the process is successful little or no contraction has taken 

 place. The object is then placed in the air and protected carefully 

 from the dust, and the turpentine allowed to evaporate. The object 

 then soou presents a very beautiful appearance ; it becomes white, 

 resembling the whitest kid. It is light, stiff, and, on account of the 

 resin it contains, is perfectly insect-proof. In annelids the iridescence 

 is perfectly kept ; hair and feather retain their original colours. 



Method of Detecting the Continuity of Protoplasm in Vegetable 

 Structures. J — W. Gardiner makes the following observations on the 

 various methods for observing the protoplasmic threads which pass 

 from cell to cell. 



During the earlier part of his work he used sulphuric acid in 

 combination with Hoffmann's violet. This latter reagent, at the 

 time of staining, colours equally protojilasm and cell-wall. If, 

 however, the section be treated for some time with dilute glycerin, 

 the staining of the cell-wall is removed, and the protoplasm alone 

 remains clearly stained. A very useful reagent for the demonstration 

 of sieve-tubes may be made by dissolving Hoffmann's violet in strong 

 sulphuric acid. After treatment with this solution the sieve-tubes 

 arc well brought into view, and all lignified tissue assumes the usual 



♦ Proc. Acad. Nat. Sci. Philad., 1884, pp. 24-7. 



t See this Journal, i. (1881) p. 70(J. 



J Arbeit. Dot, Inwt. Wurzburg, iii. (1884) pp. 53-60 (English). 



