ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 661 



culture tube, which is now reversed and introduced into a wide-necked 

 flask half-full of a concentrated pyrogallic acid solution. The surface of 

 the pyrogallic is covered with a layer of oil which, while it permits the 

 escape of superfluous gas, prevents access of air. After a few moments 

 the hydrogen has displaced most of the air. The hydrogen tube is now 

 withdrawn, and, by means of a pipette, concentrated caustic soda is added 

 to the pyrogallic acid. Any remaining oxygen is thus absorbed. 



Collecting Living Foraminifera.* — E. Heron-Allen and A. Earland 

 point out that living Foraminifera are easy to obtain and no harder to 

 preserve alive than other Microzoa : they give the result of their experi- 

 ence based on more than twenty years' collecting. The apparatus 

 required is of the simplest description : a pail, a coarse sieve with meshes 

 | in. in diameter, and a jar or tank in which to preserve the specimens 

 when caught. The horsehair sieves used by cooks are best as they do 

 not corrode, but a metal sieve will do if it is carefully washed and dried 

 after use. The writers use an enamel pail with a diaphragm of gal- 

 vanized iron wire net. If preferred a second sieve of fine bolting silk 

 may be substituted for the pail, and this is the method recommended 

 and used by J. J. Lister, but the writers use a pail for the collecting, as 

 it retains the diatoms and other microscopic organisms on which the 

 Foraminifera feed, the bulk of which pass readily through the meshes 

 of a silk sieve. 



Foraminifera are to be found in abundance in the shore-sands of 

 nearly every coast. To obtain living specimens in any numbers without 

 the use of a dredge we must have recourse to a shore on which rock 

 pools or weed-grown patches can be found between tide marks, 

 although a certain abundance can be obtained on any muddy foreshore. 

 The pail should be half filled with sea water and the sieve rested in it so 

 that the upper rim is not submerged. A handful of small weed, coral- 

 line or confervoid preferably, is then torn off, placed in the sieve and 

 thoroughly rinsed with an up and down motion of the sieve in the 

 water. All the small organisms, Foraminifera, Copepoda, and so on, 

 and most of the fine mud and diatoms adherent to the weed will pass 

 through the meshes into the pail. The process is repeated until a 

 sufficient quantity of debris has accumulated in the pail. 



For the preservation for observation of the living Foraminifera a 

 suitable tank or aquarium must be prepared. The bottom of the tank 

 must be covered with pebbles or small fragments of rock, on which green 

 seaweed, Ulva or Cladophora, is in active growth. The tank is then 

 three-parts filled with sea-water and the muddy debris poured in, the 

 surplus water being first syphoned out of the pail after the mud has 

 settled. The mud will settle down in the aquarium and fill up the inter- 

 stices between the stones. The object of the weed is to oxygenate the 

 sea-water, a method far preferable to the syringing usually recommended, 

 as it can be regulated by the amount of light which is allowed to reach 

 the tank. Moreover, when the weed is in active growth it supplies the 

 Foraminifera with food in the shape of motile zoospores. 



Before the muddy debris is placed in the aquarium it is well to empty 



* Knowledge, xxxiii. (1910) pp. 285-6. 



