1074 SUMMARY OF CURRENT RESEARCHES RELATING TO 



70 per cent, alcohol for a quarter of an hour ; half an hour in 90 per 

 cent, alcohol, and three to four hours in absolute. 



Imbedding in paraffin. Unfortunately this method is uncertain, 

 and does not allow the finer structure of the nervous system to be 

 studied. The zoochlorella retain, and this is a great advantage, their 

 green colour. 



2. After the author had convinced himself of the existence of a 

 nervous system, ho tried many dyes without result, but attained his 

 object by the simultaneous action of osmic acid and carmine. For 

 this purpose he heated a strong solution of carmine in ammoniated 

 water in a water-bath until red clouds on the surface of the purple 

 fluid arose. This shows that the excess of ammonia has disappeared. 

 After cooling, an equal volume of a 1 per cent, osmic acid was added 

 to the carmine solution, and filtered under a bell-jar. A red fluid, 

 smelling strongly of osmic acid, was obtained, and this served at once 

 as a fixative and staining ageut. The animals, placed alive in the 

 fluid, remain there for a half to twelve hours, and are then transferred 

 to 90 per cent, and finally to absolute alcohol. After some days the 

 osmic acid odour disappears and along with it the fixative power, but 

 the staining capacity of the fluid remains undiminished. It is then 

 necessary to fix objects to be examined in a 1 per cent, osmic acid for 

 two to ten minutes. The staining is as follows :- — The cell plasma is 

 but slightly stained ; the cell membrane stands out sharply, the nuclei 

 and nucleoli appear red or rose. Fat-drops are black or grey ; the 

 cilia a pale red. The zoochlorella retain their greenish hue. 



The author found iron sulphate to be an excellent fixative. In a 

 concentrated solution the animals die extended without change of 

 form. In order to save time, six to twelve Convoluta were cut at once. 

 With this intent the Convoluta are taken from the paraffin dissolved 

 in chloroform, to a glass plate coated with a thin layer of oil, and 

 arranged as desired. The plate is then placed carefully in a bath of 

 tepid paraffin, and after cooling, the whole are cut together. 



Preparing Rotatoria.* — Dr. L. Plate, in his researches on the 

 natural history of the Rotatoria,! used the following methods : — 



The animals are immersed for 10 to 15 minutes in a 1 per cent, 

 solution of osmic acid ; they are then washed and transferred for a day 

 to a 2 per cent, solution of chromate of potash, after having been well 

 washed they are stained for 2 to 24 hours in borax or picrocarmine. 

 Then alcohol with hydrochloric acid, and finally 60 per cent, alcohol. 



To obtain the animals with extended wheel apparatus, the author 

 used (1) a saturated solution of picro-sulphate of potash, 1 part, 

 and water 40 parts. They are then placed in a watchglass filled with 

 the fluid, which (2) is heated until bubbles appear. A few unfolded 

 examples will always be obtained. 



Mounting Spicules of Gorgonia.} — Mr. A. C. Cole states that to 

 make nice slides of spicules of Gorgonia a portion of the Gorgonia 



* Jen. Zeitschr. f. Naturwiss., xix. (1885) pp. 1-120 (3 pis.). Cf. Zeitschr. f. 

 Wiss. Mikr., iii. (1886) p. 239. t See this Journal, ante, p. 76. 



X Cole's ' Studies in Microscopical Science,' iv. (1886) Sec. 4, p. 7. 



