formed to its highest type, anel then draws the lines of demarcation, 

 separating group from group. Adult forms are not alone considered. 

 It follows the development of each object from its earliest condition, 

 also enlists into its service many extinct foi-ms, and by this means a 

 purely natural system is created, the series being traced from the lowest 

 to the highest creation. I have made a rough outline ot tlie system of 

 Haeckel, based on this method, which is given that you may obtain an 

 insight. In these methods many points require to be proven, many 

 obscurities to 1)6 cleared up. There is much work to be done, w^ork 

 ■which must advance slowly, but as the greater number ot leading 

 naturalists are following this plan, we can look forward to possessing, in 

 due time, a perfect system. 



Of the further division into orders, families, genera and species, the 

 two latter are the most important, as from them the name of the object 

 is derived. The species is the orie of real value, as it is the unit of our 

 systems. When among several individuals we find a peculiarity of 

 form or external marking — tangible and constant — we recognize it as a 

 specific difference, and give it a name according to some i^eculiar mai'k- 

 ing it possesses. When among several with such specific differences 

 there is a general resemblance in internal structure, and often to a great 

 extent in external characters, we recognize a natural group and name it 

 a genus. The families and orders are very unsatisfactory, the terms 

 giving no idea of their value. Their distinctions ai-e some general 

 external character which indicates a peculiarity of interna! structure. 

 Mammal orders are according to tlie hoof and teeth, birds according as 

 they are made for swimming, wading, perching, ( tc. ; insects according 

 to the character and number of their wings. It is in these lesser 

 divisions that we find the great differences of the many systems. Each 

 specialist generally works independently of those in other branches; one 

 gives a value to his divisions that another does not recognize, reducing 

 orders and making families more numerous or increasing the number of 

 orders and lessening the families. This constructing upon individual 

 authority is very detrimental to the progress of science, as is aJso the 

 custom of giving names by the same [)rimitive plan. There is hardly 

 an object that has not two or moi-e names, and in indicating it, it is not 

 enough to give a single authority, but it is becoming necessaiy to give 



