728 SUMMARY OF CURRENT RESEARCHES RELATING TO 



(2) The use of -^- NaOH in the place of ^r NaOH. 



(3) Regarding the first appearance of a pinkish tinge as the end- 

 point, instead of producing a purple red by an excess of alkali. 



(4) And, as a result of (3), adopting a reaction of + 10 instead of 

 + 15. 



(5) And finally, in adding only sufficient — NaOH to leave the 



medium of the desired acidity, rather than adding enough to render the 

 medium neutral to phenolphthalein, and producing the desired reaction 



by the subsequent addition of — HC1. 



(2) Preparing Objects. 



Method for Paraffin Infiltration. * — Mr. C. M. Thurston has em- 

 ployed the following procedure for paraffin infiltration with great success. 

 The essential feature of the method consists in applying heat to the 

 upper surface of the paraffin and of such an intensity as to melt only 

 the paraffin for a sufficient depth to submerge the tissues to be infiltrated. 

 The object lies on the unmelted paraffin, and recedes from the heat if 

 the heat increase and the paraffin melt deeper. 



Glass cups (4 cm. in diameter by 5 cm. deep) are filled with melted 

 paraffin which is allowed to cool. The cups are then placed under a 

 copper plate, which is supported over a flame by a tripod or retort-stand. 

 The flame should be at such a distance and of such intensity as to melt 

 the paraffin 1 or 2 cm. deep. 



Aceto-picric and Formalin Fixatives. — M. C. Gamier f states that 

 a mixture of formalin and picric and acetic acids gave good results for 

 fixing gland-tissue. The formula' is: — Saturated aqueous solution of 

 picric acid 30 parts, formalin 10 parts, acetic acid 2 parts. 



Herren E. O. Haltgren and O. A. Andersson J recommend the 

 following mixture which they have used for the adrenals of cats, rabbits, 

 and dogs : — 5 p.c. solution of potassium bichromate 50 grm., absolute 

 alcohol 40 grm., formalin 10 grm. 



(3) Cutting', including Imbedding and Microtomes. 



New Method for Imbedding in Celloidin.§ — Mr. E. M. Stepanow 

 has found that the following mixture answers well for imbedding in 

 celloidin : — Dry thin celloidin shavings 1 ■ 5 grm., oil of cloves 5 ccm., 

 ether 20 ccm., absolute alcohol added, drop by drop, up to 1 ccm. The 

 dehydrated object is soaked in 4-5 ccm. of this solution in a tightly 

 stoppered bottle for 3-6 hours or more. The stopper is then removed 

 to allow of slow evaporation, and afterwards the object is exposed freely. 

 As the mixture thickens the object clears up. When the mixture is 

 sufficiently thickened and the imbedding completed, the object may be 

 cut by the wet or dry method, or may be transferred to benzol in which 



* Journ. Applied Microscopy, iii. (1900) pp. 897-S. 

 t Journ. Anat. et Physiol., xxxvi. (1900) pp. 22-94. 



t Skandinav. Arch. f. Physiol., ix. No. 2, p. 5. See Zeitschr. f. wiss. Mikr., xvii. 

 (1900) p. 215. § Zeitschr. f. wiss. Mikr., xvii. (1900) pp. 185-91. 



