130 
ARE THE DESMIDS AND DIATOMS 
SIMPLE CELLS? 
By G. C. WALLICH, M.D., Surgeon-Major, Retired List, 
H.M. Indian Army. 
N ONE but those who have had long practical experience in 
microscopical analysis can form an adequate conception 
of the perplexing difficulties which are inherent in this kind of 
research. In ordinary investigations connected with natural 
history, the object to be pronounced upon may be inspected, 
handled, and tested in every possible way, by any number of per- 
sons possessed of average vision and the requisite scientific 
education, without much risk of their disagreement as to its 
visible characters. But, unfortunately, a new set of conditions 
comes into operation when the microscope has to be consulted. To 
some extent the instrument becomes an arbiter in the matter, and 
not always a very safe one. Then, it is not merely a good eye, but 
a good objective, — not merely the requisite scientific knowledge, 
but the requisite degree of manipulative skill, coupled with the 
careful training that alone qualifies the observer to distinguish 
between appearances that are real and those that are spurious 
and dependent altogether on the methods of examination em- 
ployed — which have one and all to be secured before trustworthy 
results can be achieved ; whilst the student who happens to be 
engaged in investigating the minute structure of the lowest 
organic forms is often confronted at the outset by the additional 
annoyance of being unable to reconcile what he actually sees 
in the microscope with what teachers and text-books have 
taught him that he ought to see. This last-named difficulty is 
nowhere so strikingly manifest as in studying the structure of 
these lower forms by the light of the commonly accepted defini- 
tion of the term “ a vegetable cell.” 
Now it is a singular fact that, although the cell theory 
undoubtedly constitutes the basis of all histology, and was itself 
originally propounded with reference to the lowest animal and 
vegetable types, when brought to bear specially on these very 
types, it not only breaks down but forces on us the conclusion 
