12 
TRANSACTIONS OF THE TEXAS ACADEMY OF SCIENCE. 
possible precautions to appropriately fit it to the vast array of ascer¬ 
tained biological facts. 
Surely something fundamentally wrong must be the matter with the 
leading conceptions of vitality and organization, when the explanatory 
attempts of our most prominent biological thinkers turn out to be so 
lamentably at fault. 
In winding up this critical review, I will quite briefly show how, under 
the sway of the conception of molecular vital units, another foremost 
expounder of evolution is forced glaringly to contradict the leading 
principles, which gives unity and direction to his entire sj^stem of devel¬ 
opment. It is Herbert Spencer to whom I allude. After emphatically 
declaring in opposition to spontaneous generation that “ construed in 
terms of evolution every kind of being is conceived as a product of mod¬ 
ifications wrought by insensible gradations on a pre-existing kind of be¬ 
ing,” he allows shoals of most highly constituted beings to be spontane¬ 
ously generated out of nutritive material. His physiological units, like 
the gemmules of Darwin, the plastidules of Haeckel, and the biophores of 
Weismann, are supremely endowed vital elements through whose specific 
modes of aggregation organisms are believed to be built up. In their 
peculiar constitution are supposed to be inwrought the divers character¬ 
istics to be imparted to the adult organism. The evolutional toil of 
endless ages has at last succeeded in elaborating them. And now the 
theory demands that vast multitudes of these highly wrought beings be 
newly and most speedily created, in order to afford sufficient living ma¬ 
terial for the construction of the adult organism. Unlike Darwin and 
Weismann, Herbert Spencer, and with him Haeckel and others, desiring 
to give a more mechanical aspect to their view, refrain from endowing 
their vital units with the full-fledged faculty of self-multiplication. 
They are thus driven to the monstrously anti-evolutional assumption, 
that mere pabulum through nothing but contact with preformed vital 
units becomes at once creatively transformed into their exact likeness. 
To this the fanciful transmutations of the alchemy of the medieval gold- 
makers were as child’s play. 
After having tried to lay bare the insufficiency of the molecular theo¬ 
ries of some of our most distinguished biologists, I beg leave to give an 
outline sketch of the interpretation of reproduction my own studies have 
led me to form. These studies were carried on during a number of years, 
and their principal object was to ascertain by what intimate process struc¬ 
turally unorganized, or only partly organized beings, such as protozoa, 
were empowered to perform all essential vital functions; such as motility, 
assimilation, depuration, growth and reproduction. 
I would have refrained from assuming the invidious part of a fault- 
