114 BIOLOGY: GENERAL' AND MEDICAL 



directions enabling us to create a fairly continuous series 

 in that particular line, though the members of the series 

 find no correspondence in other lines. 



This discrepancy sometimes embarrasses systematic 

 writers as they endeavor to perfect the classification of 

 living things, for a classification based upon the resem- 

 blances of adult organisms might differ widely from one 

 based upon embryological resemblances. 



FIG. 37. Fossil Diatomacese, etc., from Oran. a, a, a, Coscinodiscus; 

 b, b, b, Actinocyclus; c, Dictyochya fibula; d, Lithasteriscus radiatus; e, Spon- 

 golithis acicularis; /, /, Grammatophora parallela (side view); g, g, Gramma- 

 tophora angulosa (front view). (Carpenter.) 



In the discussion before us greater success will prob- 

 ably accrue if the living things are compared without 

 fixed ideas as to their precise position in the zoological 

 or botanical classifications. 



From the plas medium in which association of many 

 cells is followed by obliteration of the identity of each, 

 and in which it is difficult to see that the association 

 subserves any useful purpose or predisposes to the 

 occurrence of complexity through increase of size or 



