106 SUMMARY OF CURRENT RESEARCHES RELATING TO 



of tissue, and in this way saturation of the piece with paraffin is accom- 

 plished in vacuo. The blocks are easily cut on a freezing microtome, 

 yielding sections 5 /x thick. 



The most important features of this method are that vital staining 

 is retained in the sections, and Nissl's bodies are clearly evident. 



Preparing Serial Sections of Insects.* — J. B. Scriven, while follow- 

 ing generally the technique of Lowne, has introduced several time-saving 

 modifications. After the object has been fixed, it is dehydrated in hot 

 absolute alcohol and then placed straight away in the following imbed- 

 ding medium. Paraffin (45° C.) 80 grs. white wax 10 grs., anhydrous 

 creosote 2 minims, solution of caoutchouc in pure benzol (1 gr. to 5 fl. 

 dr.), 2 minims. This medium cuts well at the temperature of the 

 laboratory (16° C. circa). The sections are stretched on and fixed to 

 the slide with warm water. After allowing the ribands of sections to 

 dry by evaporation, the imbedding medium is removed by a rapid 

 flooding with benzoline, which in its turn is removed with absolute 

 alcohol. The other steps do not differ materially from those usually 

 adopted. 



Examining Oligochaetae.t — For his experiments on the regeneration 

 processes in limicolous Oligochsetse, M. Abel used Tubifex rivulorum 

 and Nais proboscidea. The regenerative parts, as well as a number of 

 normal segments, were immersed for 1 to 1^ hours in Hermann's fluid 

 ( platinum chloride-osmic-acetic acid). This solution was found to act 

 better than hot sublimate. After the preparations had been washed and 

 • hardened they were imbedded in paraffin, and then transverse and 

 longitudinal sections 5 /x thick were made. The sections were stained 

 with haematoxylin or with Haidenhain's iron-haematoxylin solution. 



(4) Staining- and Injecting. 



Fixing Neutral Red.'J — E. Golovine describes a method of fixing 

 neutral red in the tissues after intra vitam staining. The animals used 

 were Nematoda, Turbellaria, &c. The treatment of the object after 

 intra vitam staining is divided into five sections : (1) precipitation of the 

 neutral red ; (2) fixation of the material ; (3) washing and dehydration : 

 (4) imbedding in paraffin ; (5) after-staining of the sections. Neutral 

 red may be precipitated and the object fixed at the same time by means of 

 saturated solution of sublimate either alone or in combination with other 

 fixatives such as picric acid, acetic acid, osmic acid, and platino-osmic- 

 acetic acid mixture. Other fixatives mentioned are chromic acid and its 

 salts, iodide of potassium, picric acid, bichloride of platinum, and chloride 

 of gold. Washing is effected by means of saturated aqueous solutions 

 of vanadic, picric, or molybdenic acids, in picrate of ammonia, and 

 under certain circumstances in molybdate of ammonia. For dehydrating, 

 mixtures in various proportions (seven formulas are given) of water, 

 saturated solution of molybdate of ammonia and 1)0° alcohol are used. 

 The material is cleared up with toluol, xylol, and oil of cloves, after 

 which it is imbedded in paraffin. The sections must be stuck on with 



* Journ. Quekett Micr. Club, viii. (1902) pp. 343-8. 

 t Zeitschr. f. wiss. Zool., lxxiii. (1902) pp. 3-4 (3 pis.). 

 % Zeitschr. f. wiss. Mikr., xix. (1902) pp. 17G-S5. 



