ON THE NATURE OF MITOCHONDRIA 463 
symbionts enter into the formation of the reproductive organ. This 
organ which is comparable to the germ cells of higher organisms 
was first named ‘soredium’ by Acharius (from Fiinfstiick, ’07). 
Various types of soredia may be found in different lichens. In 
general, the fungal symbiont supplies a part (very much of the 
character of the spore organ in fungi) which arranges itself around 
the algal contribution (the gonidia). In other words, the algal 
symbiont is carried from one generation to another in the reproduc- 
tive element of the fungal symbiont. ‘This condition is absolute 
symbiosis in its highest development. 
This latter reproductive phenomenon indicates the solution 
to a problem that will assuredly arise in connection with a symbio- 
tic bacterial conception of mitochondria: If mitochondria are 
symbiotic bacteria, what is their source? Indeed, we would not 
seek some avenue of entrance in the adult organism nor in the 
embryonic body. The search would logically begin in the germ 
cell. The presence of mitochondria in the germ cell has been 
fully demonstrated. To seek the original source of a symbiotic- 
bacterial mitochondrium would lead us back to the dawn of 
evolution. Such an attempt, per se, is impossible. On the 
basis of biological behavior as exemplified in the absolute sym- 
biotic lichens, there is but one logical answer to the above-stated 
question: The symbiotic-bacterial-mitochondria are carried from 
one generation to another in the germ cells. 
Another question presents itself in connection with a symbiotic 
bacterial theory of mitochondria: Does such a theory harmonize 
with the known factors of cell activity? Altmann (’90) originally 
advanced the theory that the ‘bioblasts’ (mitochondria) are 
the ultimate units of life and the cytoplasm of the cells in which 
they are contained is lifeless. Altmann’s ideas, apparently, were 
chiefly theoretical. Verworn (’99) and other investigators dem- 
onstrated the untenable position of suchahypothesis. Abundant 
evidence may be offered to prove that cytoplasm, by itself, 
possesses properties that are characteristic of living matter. 
{f Altmann had limited his dissertation to a consideration of 
the ‘bioblasts’ alone, the burden of proof would have fallen on his 
adversaries. He misled his critics by introducing an erroneous 
conception of cytoplasm. This brought forth ridicule from his 
