328 SUMMARY OF CURRENT RESEARCHES RELATING TO 



be fixed in 1/4 to 1/3 per cent, platinum chloride solution for from 3 to 

 24 hours, according to size. Then, having been carefully washed in 

 water, they shoukl be transferred to weak spirit and afterwards to stronger 

 alcohols. Sections should be stained on the slide. 



Preparation of Eggs of Osseous Fishes.* — Dr. M. v. Kowalewsky 

 hardens eggs of Carassius auratus L., PoIycantJius viridiauratiis L., and 

 C. auratus L. var. for 1^ hours in a mixture of picro- sulphuric acid 8 vols., 

 1 per cent, chromic acid 1 vol. The eggs of Carassius were placed in the 

 foregoing along with the pieces of plants to which they adhered, because 

 they could not be separated therefrom without damage. The hardened 

 eggs were then transferred to 20 per cent, spirit, frequently changed, for 

 about 12 hours, and then in the course of 10 hours passed through 20, 28, 

 35, 43, 50, 60, and 70 per cent, spirit, in the last of which they were pre- 

 served. Before staining, the egg-sac was ruptured under a dissecting 

 Microscope. The stain was either Grenacher's borax-carmine, or hsema- 

 toxylin, then toluol and paraffin. 



Preparation of Heart-muscle in Cardium edule.f — Dr. K. Drost used 

 the following maceration medium introduced by Mobius : — Chromic acid 

 0*25 per cent., osmic acid O'l per cent., acetic acid 0*1 per cent., in sea 

 water. In this fluid the objects remained for some days ; acids by them- 

 selves gave no results. 



For Montacuta hidentata 1 part sea-water to 0*5 per cent, bichromate of 

 potash 4 or 6 parts were used ; but the hairs of the sense-organs were 

 found to be macerated. 



Preparation of Eggs of Arthropoda.l — Dr. F. Stuhlman in the exa- 

 mination of the eggs of insects, spiders, Myriopods, and Peripatus, 

 examined fresh objects in 0*75 per cent, salt solution, to which is some- 

 times added weak acetic and methyl-green acetic acid. The foregoing 

 was only suitable for young eggs, as older ones are too opaque. As fixa- 

 tive, cold concentrated sublimate solution proved the best. Water, 33 per 

 cent, alcohol, and hot sublimate solution were not so useful. The cold 

 sublimate fixed in 5 to 10 minutes. The preparations are then thoroughly 

 washed ; a few drops of tincture of iodine hastened the process. Then 

 60 per cent, spirit and finally absolute alcohol. The chorion is perforated 

 with a fine needle, but the upper-pole is to be avoided. Ovaries are placed 

 for several hours in chloroform, then from one to three days (according to 

 size) in paraffin at about 55^ C. The imbedding mass is rapidly cooled. 

 The sectioLS are stuck on with a thin layer of Mayer's fluid. The author 

 states that fresh albumen mass stains less easily than the older. The 

 stains used were Grenacher's borax-carmin, Weigert and Eanvier's picro- 

 carmin, and Flemming's hsematoxylin. The author recommends double 

 staining with picrocarmin and haematoxylin ; weak staining first with 

 picrocarmin and afterwards with the logwood. The dye is then extracted 

 with acidulated alcohol until a red hue appears, the sections are then 

 transferred to ammoniacal alcohol until the blue colour reappears. In 

 order to obtain various shades of colour the author advises to stain about 

 3/4 of the sections (sic) with picrocarmin and then to draw out the slides 

 from the fluid so that the upper part is more deeply stained than the 

 lower. The slide is then turned round and the process reversed with 

 heematoxylin. Afterwards absolute alcohol, bergamot oil, xylol balsam, 



* Zeitschr f. Wiss. Zool., xliii. (188G) pp. 434-80 (1 pi.), 

 t Morphol. Jahrb., xii. (1886) pp. 163-201 (1 pi.). 

 X Ber. Nuturf. Gcsell. Freiburg i. B., i. (1886). 



