512 SUMMARY OF CURRENT RESEARCHES RELATING: TO 



obtain four to six sections through the same stoma, and it is easy to get 

 several sections through the apical cell of a fern root when the imbedding 

 is properly dime. 



Dr. Schonland now writes * that since the publication of his former 

 article he lias had the opportunity of gaining more experience in the use 

 of the method, leading him to modify it slightly. In the first place ho 

 now uses absolute alcohol where he formerly only used the strong 

 methylated spirit of commerce. Further, ho now leaves specimens to be 

 imbedded for 24 hours in pure oil of cloves (after they have sunk), 

 24 hours in pure turpentine, 24 hours in turpentine saturated with 

 paraffin, and 24 hours in melted paraffin. Although much more time is 

 thus required, the results are more reliable, and he can now imbed by 

 his method without previous staining in borax-carmine, and thus consider- 

 able time and trouble are saved. 



He adds that sections fixed to the slide with collodion stain very well 

 with Bismarck brown, and can then easily be photographed. Bismarck 

 brown j stains all cell-walls. If Kleinenberg's hsematoxylin is used in 

 addition, the cellulose walls turn blue, while all other walls retain their 

 yellow colour, and thus a nice double stain is effected. If sections of 

 young tissues are treated in this way, the process of lignification in 

 vessels can be easily traced ; and if the ha3matoxylin is allowed to act a 

 sufficient time on the sections, the structure of the protoplasm will be 

 brought out. 



Celloidin-paraffin Methods of Imbedding.} — Prof. J. A. Eyder calls 

 attention to Kultschizky's method for imbedding in celloidin and paraffin, 

 which method was noticed in this Journal, 1887, p. 845. He finds that 

 it works admirably with specimens of injected spleen. The sections can 

 be cut with a dry knife on any paraffin microtome. With the author's 

 automatic microtome it is easy to cut sections 1/2000 in. in thickness 

 with the greatest ease, since a ribbon forms more easily than even in 

 the case of ordinary paraffin imbedding. The section-stretcher may be 

 dispensed with entirely, so that for consecutive or embryological work 

 the method is highly to be recommended. The author has modified the 

 original method by substituting chloroform for origanum oil, as the 

 latter is objectionable because it is disagreeable in odour, inflammable, 

 darkens in a short time, and causes the object to shrink slightly. Beyond 

 the substitution of chloroform for origanum oil there is no alteration in 

 the details of the process. 



In order to fasten the block containing the object in the holder, a 

 heated wire is used, and to make the sections form a ribbon nicely, the 

 hard paraffin used for the final imbedding may be mixed with soft 

 paraffin or paraffin gum, melting at 45° C. This method enables thinner 

 sections to be cut than with the usual wet celloidin process. 



The sections may be mounted direct from the chloroform, but the 

 operator must not allow the chloroform to evaporate before the section 

 is covered with balsam. Another method of clearing the section is that 

 proposed by Weigert, who uses a mixture of equal parts of xylol and 



* Bot. Gazette, xiii. (1888) p. 61. 



t The solution of Bismarck brown is prepared by saturating 1 part of absolute 

 alcohol with Bismarck brown and adding 2 parts of distilled water. A solution in 

 70 per cent, alcohol, as often used by zoologists, does not stain lignified cell-walls 

 very readily, and the solution in water hitherto used by botanists is said not to keep 

 very well. J Queen's Micr. Bulletin, iv. (1887) pp. 43-4. 



