394 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



Fig. 100. 



The cell-nucleus is more resistant than the plasma, except in the case 

 of potassium bichromate, which acts thereon injuriously. The size of 

 the nuclear vacuole iu which the nucleole lies greatly depends on the 

 fixative ; sublimate and mixtures containing nitric acid produce a large 

 vacuole ; while with picric acid, chromosmic acid, or Merkel's and 

 Lindsay's fluids, it quite or almost disappears. 



The structural appearances of the cell-plasma vary extraordinarily 

 according to the fixative used. Thus the plasma is more or less homo- 

 geneous with formalin, potassium bichromate, osmic acid. It is finely or 

 coarsely granular with hot water, sublimate picric acid, Merkel's mix- 

 ture, sublimate, chromacetic acid, Hermann's and vom Eath's mixture. 

 It may be filamentous or reticular with sublimate, picric acid, platinum 

 chloride. The plasma mass is very variously preserved, sometimes 

 quite tilling the cell, as with osmic acid, while with others, as chromic 

 acid, it is quite shrunk up. Some fixatives, such as formalin, produce a 

 large number of vacuoles in the plasma. 



Simple Apparatus for Rapid Dehydration. * — Prof. J. Schaffer 

 describes a simple apparatus (fig. 100) which he has used for some time 



with great success for dehydrating histological 

 objects. A square piece of platinum wire net, 

 the sides of which are aboiit 5 cm. long and 

 the meshes about 1 mm. wide, is bent into the 

 shape depicted in the illustration so as to form 

 a sort of basket. The basket is made to fix 

 itself automatically against the sides of the 

 glass jar into which it is jammed by bending 

 the corners outward. Of course the appa- 

 ratus may be used for fixing, washing, or stain- 

 ing objects, and the only disadvantage that 

 can be complained of is the dearness of the 

 platinum net. 



Celloidin Imbedding and Staining Tuber- 

 cle Bacilli in Celloidin Sections.f — Mdlle. 

 E. Wolff, in some remarks on celloidin im- 

 bedding, advises that the celloidin should be 

 treated first with absolute alcohol, and after- 

 wards with ether, as this sequence makes a 

 clearer solution than the reverse procedure. 

 The slow evaporation of the solvent mixture is 

 strongly urged, for celloidin will not remain 

 clear if direct access of air be permitted, and 

 the slower the evaporation the better the mass 

 will cut. 



For demonstrating tubercle bacilli in celloidin sections, the following 

 procedure is given. The sections are placed on slides, the superfluous 

 alcohol drained off, and the section pressed down with blotting-paper. 

 While still damp, carbol-fuchsin is filtered over the section, and the slide 

 warmed until the solution begins to vaporise. This hot-staining must 



* Zeitschr. f. wiss. Mikr., xvi. (1900) pp. 422-5 (1 fig.), 

 t Tom. cit., pp. 427-31. 



