ORGANIC DEPENDENCE AND DISEASE 
23 
perately and in easy surrender it has exceeded its first pur- 
pose and finally walled up its owners against a fighting 
chance for improvement. 
STABILIZATION, LONGEVITY AND DISSOLUTION 
Over and over again in the history of the earth we find 
the evidence of a metliuselan stability among living crea- 
tures, usually shown in definite species but sometimes per- 
meating an entire assemblage or fauna. Ruedemann has 
shown in great detail the extraordinary number of conser- 
vative types or “radicles” which have been perpetuated 
through the geological ages. It is a remarkable role of de- 
linquents . 1 
Such illustrations as these will serve : There are the pro- 
toplasmic Foraminifera which appeared in the Ordovician 
and Silurian and have kept their generic characters over 
the lapse of millions of years, to the best of our knowledge, 
into the present seas (Saccamina, Lagena, Nodosaria). The 
brachiopod Lingula lives abundantly in the existing seas ; 
its life began in the early Ordovician, and though students 
of this group believe they see some divergence in structure 
between the ancient and the existing Lingula, yet the type 
is but slightly altered and the line is unbroken over this 
enormous range of the ages. The brachiopod Crania has 
had a like career, and another brachiopod species, Lepta & * 
rhomb oidalis appeared in the Ordovician seas and con- 
tinued as a specific type through the Silurian, the Devonian 
and Carboniferous, thus caught in the world-wide conti- 
nental disturbances which brought to its close the long 
Paleozoic era. It varied indeed within limitations but re- 
tained its essential specific characters without dissolution 
for a period probably ten thousand times as long as the 
1 R. Ruedemann. ‘ ‘ Paleontology of Arrested Evolution 7 7 ; Presidential ad- 
dress before The Paleontological Society. (V. Y. State Mus. Bui. 196, 1916, 
pp. 107-34.) 
