APPENDIX (PAET II) 161 



postal order for the amount indicated below. A hatching tank complete, 

 in working order and a thousand eyed trout ova, price lls. 6d. ; a 

 hatching tank and five hundred ova, 7s. 6d. ; and a tank with one dozen 

 ova, 2s. 6d. It would be preferable to ask, however, for the eggs to be 

 sent in an earlier stage of development. 



Eggs alone, can be obtained at the rate of 10s. for a thousand, a hundred for 

 2s. 6d., and a dozen for Is. 6d. From the same fishery the eggs of other 

 fishes, numbers of aquatic creatures and water plants can also be procured. 

 See page 11. 



Series of museum specimens illustrating the development of the fish can be 

 obtained from E. J. Arnold & Son, Ltd., Butterley Street, Leeds, price 

 12s. 6d., with notes by Alfonso Gardiner, who edits the series. See 

 pages 11-13. 



Hints on the cultivation of protozoa. 



Those who have at certain times to provide for class work or otherwise, large 

 numbers of protozoa, often find it difficult or impossible to do so without 

 recourse to a dealer. With care, however, it is possible to keep many 

 kinds of protozoa so that a stock may be always at hand. 



Amoebae should be kept in rain water (not from a water butt) or pond water 

 provided it be not hard and so long as diatons are present. These may 

 generally be got in stagnant, but not fetid water. The mud at the 

 bottom, unless it be black (when the pond must be avoided) should be 

 skimmed as thin as possible, and only the very topmost layer used. The 

 head of a cod, if allowed to stand in cold water for some days, usually 

 produces first a great number of infusoria, but later, millions of large 

 colourless Amoebae admirably adapted for class work. 



Paramoccium can always be induced to appear in myriads by collecting a few 

 dead elm leaves, boiling them, and allowing the infusion to stand. Other 

 leaves favour the growth of other infusoria. Paramoecium may be fed with 

 bacteria (got by making an infusion of hay) or with oatmeal. 



Epistylis will generally be found growing on the goose-weed (Elodea). 



II L 



