1892,] The Difficulties in the Heredity Theory. 559 
we extend our inquiry into all the pan of protoplasmic 
activity. 
There are three questions before us. 
1. What is the evidence that the germ-plasm and somato- 
plasm are distinct? 
2. What is the specific nature of the germ-plasm ? 
3.What is the nature of the relations which exist between 
the two? 
1. The separation of the germ-plasm is in the regular order of 
evolution upon the principles of physiological division of 
labor. The unicellular organisms combine all the functions 
of life in a single mass of protoplasm, that is, in one cell. In 
the rise of the multicellular organisms the various functions 
are distributed into groups of cells, which specialize in the 
perfecting of a single function. Thus the reproductive cells 
fall into the natural order of histogenesis, and the theory of 
their entire separation is more consistent with the laws gov- 
erning the other tissues than the theory which we find 
ourselves obliged to adopt, that while separate they are still 
united by some unknown threads with the other cells. 
The morphological separation of what we may call the 
race-protoplasm becomes more and more sharply defined in 
the ascending scale of organisms. Weismann’s contention as 
to the absolutely distinct specific nature of the germ-plasm 
and somatoplasm has, however, to meet the apparently 
insuperable difficulty that in many multicellular organisms, 
even of a high order, the potential capacity of repeating 
complex hereditary characters, and even of producing perfect 
germ-cells, is widely distributed through the tissues. 
For example, cuttings from the leaves of the well-known 
hot-house plant, the begonia, or portions of the stems of the 
common willow-trees, are capable of reproducing complete 
new individuals. This would indicate either that portions of 
the germ-plasm are distributed through the tissues of these 
organisms, or that each body-cell has retained its potential 
quota of hereditary characters. 
Among the lower animals we find the same power; if we 
cut a hydra or bell-animalcule into a dozen pieces each may 
