538 Reed . — The Value of Certain Nutritive Elements 
in this connexion has been well pointed out by Wilfarth, Romer, and 
Wimmer (’05). 
The character of the changes which are produced when one of the 
essential elements is lacking seems worthy of attention. In the experi- 
ments which have been described above, no case was found in which the 
absence of an essential element caused serious modification in the form or 
structure of the strictly living parts of the cell. Careful observations were 
made upon different plant cells with special reference to any modifications 
of the form of the nuclei, of the amount, form, or arrangement of the 
chromosomes. No changes could be discovered which indicated in any 
way that the lack of an element caused any modification of form or 
structure in the strictly living organs of the cell. My results appear to be 
quite comparable to those obtained by Klemm (’95) in a study of the 
disintegration of the cell organs following the action of strong physical and 
chemical stimuli. Klemm found that, although deep-seated changes were 
produced in the plasmatic organs of the cell, often no morphological 
evidence of the injury could be found until death was close at hand. The 
changes of form or structure which were brought about by the absence 
of one of the essential elements were always observed in the non-living 
parts of the cell, e. g. cell-wall, chlorophyll, starch, oil, &c. For this 
reason those cells were most profitable for study which contained the most 
highly differentiated non-living bodies. The cells of the root-tips of higher 
plants do not contain non-living elements other than the cell-wall, conse- 
quently the study of those cells was comparatively unfruitful. In cells like 
those of Spirogyra which are quite highly organized, but exhibit no physio- 
logical division of labour, the lack of an essential element is most noticeable 
in a microchemical study. It should not be concluded from these state- 
ments, that the lack of an essential element has no effect upon the seats 
of the vital processes. In this connexion it is proper to call attention 
to the teratological phenomena observed by Molliard and Coupin ('03). 
These investigators found that when Sterigmatocystis (Aspergillus) nigra 
was grown in the absence of potassium, the normal form of conidial 
apparatus disappeared. In place of the normal conidiophores, variable 
outgrowths appeared. 
On the other hand, it is more than probable that the modifications 
of the non-living structures of the cell are the expressions of more deeply- 
seated changes in the activities of the living mechanism. When at length 
the absence of an essential element becomes serious enough to stop or reverse 
the normal course of activity, all activity ceases, i. e. death ensues. 
