ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
671 
properties which were sui generis , that is to say, that not-living matter 
could not, by any process we are acquainted with, take on the unique 
properties of matter which lived. Only from the living could the living 
arise. This matter was called protoplasm, and a quarter of a century 
ago was defined as “ a diaphanous semi-liquid viscous mass, extensible, 
but not elastic, homogeneous, that is to say, without structure, without 
visible organization, having in it numerous granules, and endowed with 
irritability and contractility.” 
A minute particle of this, either nucleated or non-nucleated, was 
considered a cell. 
But undifferentiated protoplasm did not long universally hold the 
field. It was gradually shown that a distinct structure was discoverable 
in some cells, and subsequently it was shown that nearly all cells and 
all forms of protoplasm show a microscopic network of fine fibres. In 
short, it became plain that the reputed structurelessness of the cell was 
due to the inefficiency of the lenses used, and was dissipated when com- 
petent optical aids were employed. 
Since this time great progress has been made, and modern objectives, 
finely corrected and of great optical precision, have been very widely 
used, and it has been shown that the nucleus, instead of being the simple 
body it was at one time believed to be, proves itself to be of great com- 
plexity ; and, as I believe, within it are initiated all the great changes 
which the cell as a whole undergoes. 
This could be shown in various ways, but I have been able to de- 
monstrate it in regard to the lowliest and least of all the organisms 
fairly accessible to us. 
The histories of the Saprophytes of this country I have been working 
at for over twenty years. It is only within the last six or seven that I 
have been able to deal with the nucleus as an optical entity to be inves- 
tigated by itself. 
In my earlier work we were obliged to study the organism as a 
whole. Our best objectives failed us when we ventured to study the 
nucleus. So we were obliged to treat the nucleus as participating in or 
sharing the life processes of the cell. It was, in fact, to us then a mere 
passive instrument. 
But homogeneous and apochromatic lenses have changed all that. 
With the objectives I can now employ I am able to deal as definitely 
with the nuclei of such saprophytes as possess them as I was twelve 
years ago with the whole organism. Yet the amplification is not greater, 
nor so great ; but that secret of all successful microscopic investigation, 
a numerical aperture suited to the amplification used, is at our disposal, 
and this with the ghosts of injurious spectra taken away. 
The result is a discovery that the apparently simple nucleus of the 
lowliest and the least of known organic forms is complex in a high 
degree ; that it is the spring and fountain of vitality in the cell. All 
modifications to which the cell is subject in its life cycle originate in it. 
It is, moreover, at certain periods of development of the cell endowed 
with striking structure, and this structure grows more or less marked as 
the unicellular organism enters upon or passes certain cyclic periods of 
change. 
In brief, the nucleus of the simplest of living cells is complex in an 
