472 SUMMARY OF CURRENT RESEARCHES RELATING TO 



and a few drops of the emulsion deposited on the surface of the medium 

 in one of the plates by means of a platinum loop, resting the lid of the 

 plate on the bench during the process of inoculation. (6) Smear the 

 suspension over the surface of the medium by means of the short-arm 

 of an L-shaped sterilised glass rod. (7) Without sterilising or re- 

 charging the rod smear the surface of a second plate, then a third, and 

 if necessary a fourth. (8) Cover the plates, invert them, label the 

 under surface which now is uppermost, and incubate (still in the inverted 

 position) at 37° C. 



Nets for Gathering Plankton.* — J. Richard describes two nets for 

 obtaining plankton. The first is made of coarse packing cloth at about 

 bd. a yard. The cloth is attached to a strong square iron frame, the 

 sides of which are 3 metres long. The length of the net is about 

 G metres, and its bottom is formed by a pail supported by means of 

 cords to the iron frame. It is heavily weighted, and is employed for 

 gathering at considerable depths. The other is a simple net 50 cm. 

 long, with an opening of G cm. This is allowed to trail on or near 

 the surface. Both nets have given great satisfaction and are very easily 

 and cheaply made. 



(2) Preparing- Objects. 



Fixative Solutions Isotonic with Sea Water.f — M. C. Dekhuyzen 

 makes a fixative solution isotonic with sea water by mixing 250 c.cm. 

 of 2 • 5 p.c. potassium bichromate dissolved in filtered sea water ; to 

 this, 25 c.cm. of G"3 p.c. nitric acid and 54 c.cm. of 2 p.c. osmic acid 

 are added. The specific weight of this fluid is 1*038 at 20° C. Its 

 great advantage is that it can be mixed with sea water without altering 

 the osmotic pressure. It fixes the blood-cells of Sipunculus nudits 

 admirably, and is equally successful with other organisms such as 

 Oydippa, Terebellina, etc. For fixing organisms which contain cal- 

 careous matter, such as larvae of sea-urchins, the author has devised 

 an isotonic fluid which does not contain free acid. This is prepared by 

 mixing 26" 9 c.cm. of 2 p.c. osmi: id and 173 '1 c.cm. of 2*5 p.c. 

 bichromate of potash in filtered sea mv &r. 



Picroformol for Fixation. $ — A. Guilliermond, for studying the 

 formation of asci and the epiplasm of Ascomycetes, used Maire's modi- 

 fication of Bouin's picroformol. Formalin 40 p.c, 30 grm. ; acetic 

 acid, 5 grm. ; distilled water, 20 grm. Picroformol to saturation. 



Preparing, Staining and Mounting Fresh-water Fauna. § — K. 

 -•-i— recommends a funnel-shaped silk gauze net for catching 

 ._ fauna, which should be transported to the laboratory in 

 glass vessels. The great secret of obtaining a successful preparation 

 depends on the skilful use of narcotics. These should be used in very 

 dilute solution, and the palsy of animals awaited with patience. The 

 animal to be mounted should be removed with a pipette to a slide, and 

 on this the rest of the manipulation carried out. The narcotising fluid 



* Comptes Kondus, cxxxviii. (1904) pp. 1436 -7. 



♦ Tom. cit., pp. 415-7; 445-7. J Rev. gen. Bot., xvi. (1904) p. 49. 

 § ZcHsdiv. nrgew. Mikr., x. (1904) pp. 5-8. 



