298 
R. A. HARPER 
some very small chromosomes, and a Micrococcus with all the characters 
necessary for growth, life history, and reproduction is again of about the 
same size. 
Our positive knowledge of the size of both protein and carbohydrate 
molecules is very limited, but the figures given indicate that for example 
the linear dimensions of the chromosomes of the ordinary form of Primula 
Kewensis are some hundreds of times those of the molecules of starch and 
haemoglobin. There is ample space in these chromosomes for a number of 
molecules equal to the most extreme demands of the factorial hypotheses 
if each factor can be represented by a single molecule or even a group of 
molecules. These particular chromosomes too are by no means large. 
I have chosen them as illustrations because Farmer and Conklin respectively 
seem to have measured them with unusual care. 
It is sometimes suggested that a factor may be embodied in a single 
molecule or by a mass of a single compound. It seems probable that colors 
and similar metidentical characters are due to single compounds or mixtures 
of a few compounds in the cells of the metaphyte body. That however the 
complex of cellular interactions including the regulation of the order and 
relative number of a whole series of cell divisions such as are involved in 
producing the serratures on the margin of a leaf can be represented by a 
molecule or group of molecules in a chromosome is hard to conceive. It 
would seem more natural to regard such organic regulations as the expres- 
sion of the capacities for interaction of the complex cell mechanism as a 
living unit in its entirety. The delicately balanced and adjusted 1-5-10 
relation between the cells of a bilaterally symmetrical sixteen-celled colony 
of Pediastrum Boryanum seem to be achieved by the interactions of the 
swarmspores acting as independent units each with a definite polarized 
organization and capacity to respond to delicate contact and pressure 
stimuli. 
In any case we need more evidence as to the size of protein molecules 
before comparisons of the size of molecules and chromosomes can have 
much significance. Of more importance at present is the well-established 
evidence of specific mass relations between the various parts of the cell 
unit as a whole considered as a polyphase system, though here again the 
significance of the facts in their relation to the problem of protoplasmic 
organization is not yet clear. Strasburger had shown in 1893 that there is a 
tendency in young meristematic plant cells to the maintenance of a con- 
stant volume relation between the nucleus and the cytoplasm, the ratio of 
nuclear diameter to cell diameter being something like 2 13. 
Gerassimow in his classic discoveries of methods for producing and cul- 
turing binucleated cells in Spirogyra and other members of the Conjugatae 
established experimentally the existence of a nucleo-cytoplasmic relation 
of mass in these forms, as have R. Hertwig and Boveri for various animal 
types. Gerassimow's data, however, do not cover the problems of chro- 
