770 SUMMARY OF CURRENT RESEARCHES RELATING TO 



•being taken not to injure the section. The flame is then extinguished, 

 .and the section pressed firmly to the slide until the balsam hardens. 

 The free side may then be ground down on a whetstone to any desired 

 thickness. 



Contributions to the Theory of Fixation, with Particular 

 Regard to the Cell-Nucleus and its Albuminous Bodies.*— W. Berg 

 in an important paper gives the results of his experiments on the 

 individual effects of 24 fixing agents on nucleins and nucleic acids from 

 various sources, and on other bodies, such as clupein — a representation 

 of the protamines— both by itself, as a sulphate, and in combination 

 with nucleic acid. Although sometimes larger quantities were used, a 

 drop of a filtered solution was usually taken — generally in 2 p.c. KOH— - 

 of the proteid substance, and mixed with one or more drops of the fixing 

 agent on an ordinary microscopic slide. The effect was then observed 

 .as regards (1) the presence or absence of precipitate, (2) its water- 

 solubility, and (3) the forms taken by it. The last the author groups 

 into (a) cbagula and granular films, (b) granules, and (c) hollow bodies. 

 He does not claim that the results of his experiments constitute a reliable 

 index to the effects of fixing agents on tissues or on cells, the proteids 

 existing in them not being "identical with those of the solutions experi- 

 mented on. Moreover, the behaviour of the representative of a group 

 of bodies such as the nucleic acids is not constant, but varies with the 

 ■origin of the substance. For example, acetic acid causes no precipitate 

 with nucleic acid from soft roe of the herring, but with that derived 

 from yeast there is a marked precipitate. Neither are the results with 

 clupein constant with protamines in general. Space will not permit 

 even a resume of the experimental results. The apparent lack of effect 

 ■of formalin is however striking. The So p.c. alcoholic _ solution of 

 sublimate is much superior to the 7'5 p.c. aqueous solution. Osmic 

 acid precipitates neither nucleins nor nucleic acids, while alcohol, acetic 

 acid and, above all, chloroform-alcohol-acetic acid have the strongest 

 •effect on them. 



(3) Cutting 1 , including: Imbedding- and Microtomes. 



Manipulation of Sections of Leaf Cuticle.f— S. M. Bain takes a 

 very narrow strip of the leaf and embeds it in paraffin. _ The paraffin 

 is trimmed away under a lens until the surface to be cut is reduced to a 

 minimum. The sections, cut off in scrolls, are placed on a small drop of 

 ■distilled water on the centre of a slide. Here they usually unroll of their 

 own accord ; if not, slightly warming may flatten them out. The water 

 on the slide is allowed to evaporate spontaneously, and when dry the slide 

 is warmed until the paraffin just begins to melt. The rest of the pro- 

 cedure is similar to that usually followed. 



Imbedding in Celloidin.*— C. H. Miller recommends the following 

 method. Into the wide mouthed cork-stoppered bottles are placed 

 .solutions of celloidin of graduated strength, each 100 c.cm. containing 



* Arch. Mikr. Anat, lxii. (1903) pp. 367-430. 



+ Jouru. App.Mikr., vi. (1903) pp. 2160-1. * Tom. cit.. pp. 22o3-4. 



