632 SUMMAEY OF CUEEENT EESEAECHES EELATING TO 



tically in sterile test-tubes, which are thereafter maintained at a 

 temperature of 20°-30° C. Motile forms begin to show themselves on 

 the third day, and reach the maximum between the tenth and four- 

 teenth day. 



Asbestos Filter.* — 0. Bujwid describes a method for filtering 

 cloudy or turbid liquids. This consists in shaking up the liquid with a 

 small quantity of asbestos and then filtering the whole, a completely 

 clear liquid resulting. The author has employed this method not only 

 for clearing broth and gelatin, but also for turbid liquids containing 

 bacteria. It is, however, not suitable for filtering fluids used for the 

 preparation of diphtheria toxins. 



Collecting and Preserving Medusae.! — E. T. Browne has used the 

 following methods for some years. A small, flat hand-made net of 

 bolting silk is useful for catching medusfe swimming at the surface. 

 For towing nets the following sample is described. It has a circular 

 mouth 17 inches in diameter, and the net is about 5 feet in length, 

 gradually tapering down to 3| inches in diameter, which is the diameter 

 of the zinc can attached to the end of the net. The nets are made of 

 bolting-silk ; three nets form a series with 30, 50, and 70 threads 

 respectively to the inch. 



The speed of towing the net is important, and the speed is about 

 right when the line can be comfortably held on one finger ; this 

 amounts to about a 3-lb. pull. 



"When the net is taken on board, the contents of the can should be 

 poured into one or more glass vessels. The medusae are then picked 

 out and placed for half an hour or more in another vessel until they 

 have recovered from the shock. If they lie heaped up at the bottom 

 of the vessel they should be stirred up with a glass rod. The medusEe 

 are quickly fixed and preserved by means of formalin (5-10 p.c), but in 

 order to do this successfully they must be kept in motion liy stirring 

 up with a glass rod while the formalin is slowly poured in. After a 

 few hours they are transferred to 10 p.c. formalin, changed once before 

 sealing up the bottle. 



To obtain medusa? in a nice state of expansion, it is necessary to 

 use an ana3sthetic. Add about 3 c.cm. of 1 p.c. cocain for every 

 100 c.cm. of sea-water, stirring gently the while with a glass rod. If 

 in from 10-15 minutes the tentacles are expanded, and do not contract 

 when touched with a glass rod, no more cocain need be added, but if 

 still active the process must be repeated. When the medusas are 

 an^sthetised, stir them round gently, and add the formalin, still stirring 

 the while. Specimens must not be left too long in a cocain solution, 

 as it has a softening action. 



For Scyphomedusse the addition of chromic acid is an advantage. 

 The author uses one vol. 5 p.c. chromic acid and nine vol. 10 p.c. 

 formalin. After soaking for several days in the chromic-formalin 

 solution, to which a little strong formalin is added daily, the specimen 

 is transferred to 10 p.c. formalin for permanent preservation. 



* Centralbl. Bakt., Ite Abt. Orig., xliv. (1907) p. 191. 

 t Trans. Linn. Soc, Zool., x. (1906), pp. 163-80 (1 pi ) 



