1892.] Heredity of Acquired Characters. 897 
becomes a marked peculiarity of the females of the family, that 
is persisted in under better conditions of food supply. 
It appears to be unnecessary to assume fortuitous changes 
in the germ cells to account for the increase, or the suspension 
of functions that can be so clearly traced to an acquired ances- 
tral habit. Morphological peculiarities are not the only ones 
that give character to an organism and determine its signifi- 
cant qualities. As in isomeric compounds in chemistry, we 
find living organisms that are, so far as we can determine, 
morphologically identical, that differ widely in their habits 
and general properties. Even in the higher animals the same 
organ may perform a variety of functions, as the liver for 
example, and the dominant function for the time being seems 
to be determined by the requirements of other organs, or of the 
general system under the special conditions in which it is 
placed. 
There are many species of microbes having the same form 
and structure that are distinguished by their habits, or the 
katastates formed in their processes of metabolism, and these 
katabolic products known as toxines, tox-albumins, and pto- 
maines, &c., differ widely in their specific properties. Pecul- 
iarities in the functional activity of certain organs, or of the 
general system, appear to be transmitted with the same uni- 
formity and certainty as morphological characters that are 
more readily observed, although not more significant as dis- 
tinguishing characteristics. 
The experiments of Dr. Dallinger with three species of 
monads, under prescribed conditions of temperature are of 
particular interest in showing that the modified or acquired 
habits of organisms are beyond question transmitted to their 
offspring. From the rapid repetition of the process of repro- 
duction in these organisms, by fission and sexual fusion, they 
have marked advantages in experiments for determining the 
inheritance of new characters. 
Throughout the experiments an abundant supply of suitable 
food was provided, and beginning with a temperature of 60°, 
which appeared to be the most favorable for them, a gradual 
increase of temperature was made from time to time as they 
