634 SUMMARY OF CURRENT RESEARCHES RELATING TO 



properties are similar ; ozokerite is not so hard as beeswax, and its 

 boiling-point is a little lower. It is also paler in colour, and most tran- 

 sparent. Beeswax, moreover, costs three or four times as much as 

 ozokerite. The author describes a rack of simple construction for 

 drying the wax plates. The plates rest at two points on their lower 

 edges on horizontal slats, and are slun^ at a slight angle from the 

 vertical upon string loops. The plates are arranged to have the greatest 

 possible amount of air space between them, and the slinging method 

 permits access of air to the whole surface. 



Dehydration and Paraffin- embedding".*— H. Fischer considers that 

 the practice of dehydrating botanical objects to the highest possible 

 degree before embedding in paraffin is not to be recommended. He 

 failed to get satisfactory results by such means, but by using 92-95 p c. 

 alcohol instead of absolute alcohol, and transferring from this to a 

 chloroform — 95 p.c. alcohol mixture and thence to chloroform — he 

 obtained much better preparations. The author defends his method on 

 physico-chemical grounds. 



Method of Preparing* Tendon Sections. t — M. Heidenbain discusses 

 methods of treating this material in order to obtain sections for class 

 purposes. The method of treating with trichloracetic acid and alchol, 

 and embeddinii: in celloidin has the disadvantas^e that the sections are 

 difficult to stain suitably. He recommends that dried tendons be cut 

 in as thin sections as possible, freehand, with a sharp scalpel. Such 

 sections are dropped into distilled water to unroll. They are naturally 

 of unequal thickness and unsuitable for fine histological Avork. Stained 

 with dilute ruthenium red solution they make good preparations. The 

 sections are left in this stain for an hour or so. The tendon-cells and 

 connective-tissue-septa are rose-red, the tendon-fibres almost colourless. 

 Such preparations keep well in 10 p.c. alcohol for a v»'eek or so. For 

 examination by students, they are mounted in water or alcohol. They 

 are not suited for permanent preparations. 



Another method is as follows ; a portion of calf's tendon is fixed in 

 Miiller's fluid, hardened in alcohol, and 1 cm. length embedded in 

 celloidin. Longitudinal sections, 80 /x in thickness, are stained for 

 twenty-four hours in Delafield's hsemotoxylin, made alkaline, and treated 

 with an alcoholic solution of chromotrop. They are transfered to alcohol 

 and then to creosote. These sections are then handed to the students, 

 carefully teased and mounted. Tendon cells and fibrils are well shown. 



Preparation of Paraffin for Embedding Purposes.^ — B. Farkas 



refers to tlic views of various writers upon the best methods of paraffin 

 embedding, and the question whether slow or quick cooling of the block 

 gives the better results. He considers that blocks are unsatisfactory for 

 section purposes when their homogeneity is broken by air-bubbles, and 

 recommends a special treatment of paraffin before it is used for embed- 

 ding. On arrival at the laboratory, it is placed for a Aveek or longer in 



* Zeitschr. wiss. Mikrosk., xxx. (1913) pp. 176-7. 

 t Zeitschr. wiss. Mikrosk., xxx. (1913) pp. 161-7. 

 X Zeitschr. wiss. Mikrosk., xxx. (1913) pp. 168-74, 



