202 BIOLOGICAL LECTURES. 



In the second or taxonomic collection, the central idea in- 

 spiring the whole should be to dispose types of species or 

 genera so that these will link together and illustrate each other, 

 at the same time that they represent in natural relation a 

 family or order. Details can be worked out here that will 

 suggest themselves to any reflecting mind. Under the third 

 department more has already been done than under either of 

 the former, but great possible advances are still in the future. 

 A series of preparations of the black-knot fungus (PlowrigJitia 

 morbosa), and of others whose life r61e is simpler or more com- 

 plex; a series of the flowering parasites and their relation to 

 host; all the life forms of gall insects and the appropriate gall 

 formed by each species or life-phase of a species, such are a 

 few of the biological problems that can be graphically and 

 permanently illustrated. 



All who have had to do with the arrangement of museum 

 specimens know that the lighting of a museum building is a 

 prime consideration. Where the smaller details of floral 

 structure are to be traced, the placing of the jars in some 

 badly lighted room is tantamount to the concealment of knowl- 

 edge. But, granting that the lighting is all that could be 

 desired, the eye can often be helped by a specimen being 

 arranged against an appropriate background, a black one, for 

 example, in the case of all bleached preparations. 



Finally, it cannot be too strongly emphasized that such 

 specimens should not be handled loosely, or passed round in a 

 class-room. Equally important is it that in the original selec- 

 tion and disposition of a plant in a jar, care should be exercised 

 to have every feature displayed toward one side of the jar, so 

 as to obviate the necessity of its being turned round. This 

 can readily be done in nearly every case. 



(/) Description of preparations. After each jar has been 

 assigned to its proper place, there remains the work of descrip- 

 tion. This should not, as in most museums of the past, be a 

 bare statement of the species and order to which the specimen 

 belongs, but be so elaborated as to guide the observer to an 

 intelligent appreciation of the features that the specimen pre- 

 sents. 



