EVIDENCE OF INORGANIC EVOLUTION 587 



also the other evidence) for so regarding it in the case of the ele- 

 ments also. 



One other analogy demands recognition. Although, as previously 

 stated, the phyla of organisms differ widely from each other, yet animals 

 belonging to different phyla often show marked resemblances to each 

 other in particular features. This phenomenon is a consequence of 

 " the identity of plan, under the most diverse conditions of organization 

 and habits of life (which prevails) not only among animals of the same 

 group, but also between those of different groups." 9 For instance, 

 regarding the affinities of the Eotifera (Phylum Trochelminthes) 

 Parker and Haswell 10 state that 



Their general resemblance to the free-swimming larvae of Annelids is 

 extremely close. . . . The excretory organs recall those of Platyhelminthes, and 

 also resemble the provisional nephridia or head-kidneys of Annulate larvae. 



Resemblances are also noted between the Class Gephyrea (Phylum 

 Annulata) and Phoronis (Phylum Molluscoida). 11 The Crustacea 

 (Phylum Arthropoda) "belong to the same general type of organiza- 

 tion as the articulated worms [Phylum Annulata] ." 12 Of the Phylum 

 Mollusca it is stated that 



The Mollusca . . . form an extremely well defined phylum, none of the adult 

 members of which approach the lower groups of animals in any marked degree. 

 There are, however, clear indications of affinity with "worms," especially in 

 the frequent occurrence of a trochosphere stage in development, in the presence 

 of nephridia, and in the occurrence, in AmpMneura and some of the lower 

 Gastropods, of a ladder-like nervous system resembling that of some Turbellaria 

 and of the most worm-like of Arthropods, Peripatus. Rhodope, moreover, shows 

 certain affinities with flat worms. 13 



Similarities are also pointed out between the sponges (Phylum 

 Porifera) and the Ccelenterata. 14 



Corresponding to these counter-resemblances in structure among 

 organisms, we have counter-resemblances in properties among the ele- 

 ments. Thus, mercury (Group II.) resembles copper (Group I.) in 

 that both form two series of compounds, monovalent and divalent re- 

 spectively, both form halides insoluble in water and decomposed by light, 

 etc. Aluminum (Group III.) is similar to chromium (Group VI.) in 

 that the hydroxides on heating give the oxides Cr 2 3 and A1 2 3 , re- 

 spectively, in that they form no stable sulphide or carbonate, etc. 

 Thallium (Group III.) resembles, on the one hand, lead (Group IV.) 

 in its metallic properties, in forming a chloride with properties similar 

 to those of lead chloride, while, on the other hand, it resembles the alka- 



9 Claus and Sedgwick, "Zoology," Vol. I., p. 54. 



10 "Zoology," Vol. I., pp. 309-310. 



11 Parker and Haswell, loc. tit., p. 461. The zoological classification fol- 

 lowed throughout is that given by these authors. 



12 Parker and Haswell, loc. eit., p. 556. 



13 Parker and Haswell, loc. tit., pp. 750-751. 

 "Parker and Haswell, loc. tit., pp. 215-216. 



