102 NATURALISTS’ ASSISTANT. 
debted for the present low state of the microscopical branches 
of biology. These men without knowing the first requisite 
of biological work have denounced good instruments and 
advocated useless ones, have based their opinions of the 
worth of an instrument on its power of resolving diatoms, and 
the result is that the beginner, influenced by their dogmatic 
assertions and widely-copied opinions, has been led to pur- 
chase an instrument wholly unsuitable for his ends and the 
result has been discouragement and a cessation of microscopic 
work. 
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