756 SUlIilARY OF CURRENT RESEARCHES RELATING TO 



ditions clearly differentiates them from the other portions of the 

 protoplasm. 



For the same object acetic acid and cochineal are used. Stras- 

 bnrger * immerses the preparations in acetic acid, washes them in 

 distilled water, sometimes neutralizing the acid by a weak alkaline 

 solution, and then uses the tincture of cochineal. Guignard f jirefers 

 cai-mine to this reagent for studying the nuclei in the embryo-sac 

 and the suspensor of the Legumiuosfe. He dissolves it in a mixture 

 of 1 part of water, 2 parts of absolute alcohol, and 1 part of glj cerin 

 containing borax. 



Poulsen I gets the solution of carmine fur colouring the nuclei by 

 warming • 6 gr. of carmine in 2 gr. of ammonia until the solution is 

 reduced to half its bulk ; he adds to it 60 gr. of water, 60 gr. of 

 glycerin, and 15 gr. of absolute alcuhol. The liquid is allowed to 

 stand until clear, and then filtered. 



The author has used the carmine to follow the curious pheno- 

 menon of the fragmentation of the nuclei in the hypertrophied cells 

 in conseqiience of wounds. § He has obtained an excellent result with 

 haematoxylin. Although an extract of logwood, this substance only 

 exists in very small quantity in the tincture of logwood. 



The method indicated by Poulsen H is to use • 35 gi\ of powdered 

 hfematoxylin in 10 gr. of water ; a few drops of a filtered solution of 

 alum containing 3 gr. of alum to 30 gr. of water are added to it to fix 

 the colour. ^Vhen the preparations remain for some time in haema- 

 toxylin thus prepared, the nuclei are coloured a fine blue. Picro- 

 carminate of ammonia (or Eanvier's picrocarmine) is also of great use 

 in the study of nuclei, both in the Phanerogams H and in the Micro- 

 phytes and Infusoria.** For the latter Certes j| thus prepares the 

 solution of this reagent : — glycerin, 1 part ; water, 3 parts ; picro- 

 carminate, 1 part. 



The colouring is effected either after the fixing by osmic acid or 

 independently of the action of this acid. 



These various reagents may be employed (provided theii* concen- 

 tration be varied) for studying in the midst of the protoplasm the 

 minute structiu'e of the nucleus, the nucleoli, the mode of distribution 

 of the chromatin, all the phenomena of the division, the formation of 

 the " barrel," of the equatorial plate, and the poles, &c. On this 

 subject may be advantageously consulted the papers of Baranetzki,:{:| 

 Zacharias,§§ Strasburger,|] || Schmitz,*'^ Treub,*** and Guignard,tif 

 and the resume of their works given by Van Tieghem in his ' Traite 

 de Botanique,' in course of publication. |i:j: 



* 'Studien iiber Protoplasma,' 1876. t Ann. Sci. Nat, xii. (1881). 



J Loc. dt., p. 42. § Bull. Soc. Bot., lUth JIarch, 1882. 



II Loc. cit., p. 46. ^ Poulsen, loc. cit., p. 46. 



** Cf. Kanvier, ' Traite d'Histologie.' 



tt Compter Een.lus, 3rd IMarch, 1S79. JJ Bot. Ztg., 1880. 

 §§ " Ueber die chemiBche Beschaffeuheit des Zellkerus," Bot. Ztg., 18th March, 

 1881. See this Journal, i. (1881) p. 769. 



nil Loc. cit., 18S0. «[[1[ SB. Naturf. Gesell. zu Halle, 1878 and 1879. 



*** Arch. Ne'crland., xv. (1880). 

 ttt Loc. cit., 18S1. ill P«ris, 1882. Fasc. 4, pp. 343, &c. 



