1870.] 217 [Edwards. 



has been more cursed with supposed discoverers of this class than the 

 Diatomacese, until a man comes to be appreciated by the number of 

 species he can manufacture. By far the largest number of observers 

 who are attracted to these beautiful and wonderful atomies forget that 

 we have in them presented to us for investigation one of the most 

 puzzling problems in the Avhole group of phenomena, illustrating that 

 which we call life, but on the contrary appear to consider them as 

 M simple organisms," whose morphology and life history, as well as 

 classification, are therefore proportionally easy of comprehension. I 

 have devoted many years to the earnest study, under varying condi- 

 tions, of these examples of complex simplicity, and pity it is that others 

 who have not spent so much time over this branch of organic exist- 

 ence should not have been so fortunate as I was in possessing a wise 

 and patient counsellor in the late Dr. Walker Arnott. I can truly 

 say that had it not been for his invaluable friendly advice, I, too, 

 would have doubtless ranged myself with the manufacturers of species 

 and synonym accumulators. Often have the kindly words he has 

 written me made me pause ere I, as he pithily remarked, " rushed 

 into print " with supposed discoveries, which I would have been 

 ashamed of thereafter. Dr. Arnott says " a microscopist looks on 

 everything as subservient to the microscope, and that whatever he 

 sees, and which appears distinct to the eye, he thinks ought to be de- 

 scribed or figured as distinct. I am, on the other hand, a naturalist, a 

 botanist in particular, and use the microscope, simple or compound, 

 as a necessary evil, merely to enable my eyes to see better minute 

 structures, but whether these differences amount to specific or generic 

 importance, or are only peculiar forms of one species, is the result of 

 analogy, a mental process which can only be attained by a training in 

 botany in all its branches, for many years." Natural objects, like the 

 Diatomacese, which can only be seen after they are magnified several 

 thousand times, and then only under peculiar circumstances of illu- 

 mination, must be difficult of comprehension, even if their life history 

 were much more simple and more easily studied than it is. I cannot 

 too strongly caution the intending student of this enticing branch 

 against trusting to a few and hasty observations made upon the dead 

 skeleton of the plant. It is only when they are studied in the living 

 state that the Diatomacese can be understood, and even then only with 

 difficulty. 



But one more abstract from my note book and I must draw these 

 remarks to a close. In the early part of November, 1868, I made a 



