ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 665 



from time to time with a glass rod. The carbonic acid then bubbles up 

 and escapes, and at the same time numerous Foraminifera collect on the 

 surface. The explanation of this is simple. Small bubbles of the gas, 

 owing to the heat, are developed and become entangled in the shells of 

 the Foraminifera, and the latter are raised to the surface. The 

 Foraminifera may then be skimmed off with the sieve used for diatoms. 



Permanent preparations are made by placing the Foraminifera thus 

 obtained in absolute alcohol in order to expel the air. They are then 

 cleared up in oil of cloves or xylol, and mounted in Canada balsam. 



Preparing Sphaerozoa.* — For examining living Spheerozoa, Dr. K. 

 Brandt recommends the use of a polarizing apparatus and also staining 

 the organisms while alive. He points out that while • 1 per cent, 

 osmic acid fixes well, its value is discounted by the great blackening it 

 causes, especially of the pseudopodia. The author notes also that all 

 Sphferozoa are not equally susceptible to the action of the same reagent. 

 (1) For Collozoiim inerme, C. jpelagicum, C.fulvum, Sphserozoiim pundafum, 

 S. acuferum, and S. neajjolitanum, the most advantageous is a tincture of 

 iodine (1 part 70 per cent, spirit ; 1 part sea water ; and so much 

 tincture of iodine as will impart a distinctly yellow colour to the mixture). 

 The tube in which the animals are killed is very gently shaken, and 

 after 15-30 minutes its contents are washed with water to remove the 

 sea salt, and then the colonies are removed to spirit of 30, 50, and 70 per 

 cent, successively. (2) Myxospliaera cseridea, Collosphsera Huxleyi, and 

 Aerosphsera spinosa are well fixed in • 5 to 1 • per cent, chromic acid. 

 After having been well washed they are transferred to 30, 50, and 

 70 per cent, spirits. By the iodine tincture the jelly of the species last 

 mentioned is either dissolved or completely altered in form, while those 

 mentioned under number (1) with the exception of S. acuferum, lose their 

 jelly by the action of chromic acid, or at least their shape is damaged. 

 (3) Strong solutions of picric acid (and picro-sulphuric acid too) behave 

 like weak solutions of chromic acid. The species given under (2) retain 

 some connection, but in the others the jelly is dissolved. (I) Hydro- 

 fluoric acid fixes the plasma well. (5) A 5 to 15 per cent, solution of 

 sublimate in sea water retains the shape of C. pelagicum, S. pundatum, 

 S, neapolitanum well (after acting 15-30 minutes they are well washed 

 in sea water, then in sweet water ; afterwards alcohols 30, 50, 70 per 

 cent.). The most useful stain was found to be a watery solution of 

 haematoxylin, but for Collosphsera Huxleyi Grenacher's alcohol carmine. 

 Besides these were used dahlia, the other carmine solutions of Grenacher, 

 and Mayer's alcoholic cochineal solution. 



Preparation and Mounting of Ferns-f— Mr. J. D. King remarks 

 that the selection of the fern is all-important. It should be of robust 

 growth and free from dirt. If not fully ripe the spores will be shrunken, 

 if over ripe, absent. Have ready wide-mouthed bottles, to hold about an 

 ounce, and filled with a mixture of equal parts of spirit and water. In 

 this place the selected pinnae. 



If the pinnae are to be kept for some time, add one-fourth part 

 spirit, put only one kind in a bottle, avoid shaking the bottles, and 

 handle the material with forceps without touching the sori. 



For bleaching, the following mixture is successful : — Dry chloride of 



* Fauna u. Flora d. Golfes v. Neapel, siii. (1885) 276 pp. (8 pis.), 

 t The Microscope, viii. (1888) pp. 78-81. 



