156 JOURNAL OF THE [December, 



conviction that the diatoms I was raising had no originative 

 connection with those diatoms in the old sediment. 



It was the beginning of March. 1 had given much thought 

 to this subject, and I now proceeded to make a crucial exper- 

 iment — not that its failure would disprove anything, but that 

 its success would, I thought, demonstrate the correctness of my 

 conviction. This was set down as experiment No. 4. The 

 demijohn was again resorted to, and from it into a jar similar 

 to the preceding ones, water, equal in amount to what each of 

 them contained, was passed through druggist's filtering paper. 

 This done, the jar, labelled C, and covered with glass, was 

 placed beside B in the window. 



At this point in my experiments, I collected as well as I 

 could all the diatomaceous material in jar A, my first experiment, 

 put it in a small phial, which, together with a letter, I sent to 

 Prof. H. L. Smith. In my letter, which was written and posted 

 on the 1 2th of March, 1883, I did not mention that the diatoms 

 had been raised in my study, but simply said that they had been 

 obtained from water which came from Raritan Bay. I received 

 from him a letter, also a mounted slide of the diatoms. This 

 slide I have here under a microscope for your inspection. I 

 have here also a number of slides of those diatoms mounted by 

 myself. The Professor's letter stated that the slide contained three 

 genera, Nitzschia, Amphora^ and Navicula ; and that the Nitzschm 

 were by far the most numerous, the AmphorcB next in number, 

 and the Naviculce least. 



About the end of March, 1883, appeared that, to me, welcome 

 sign, the yellowish-brown film on the bottom of jar C. Almost 

 nervously I took a drop of it with a pipette, put it on a slide, 

 and then placed the slide under the microscope, and what a 

 sight ! The diatoms were there in immense numbers, many of 

 them in lively motion. The Nitzschicz and NaviculcB were of 

 larger size than those in crops A and B. But this crop C yielded 

 forms entirely new, and in numbers that would thrill a species- 

 monger with delight. Of the symmetrical forms, five figures are 

 given in the plate, i, 2, 2*, 2^, 2°. Figure i with its beaded 

 borders and trim geometrical lines is an exquisite form, but is 

 rare. Figure 2, a pretty, truncated ellipse, is of interest as con- 

 stituting the nucleus in such nests or series of layers as are 

 shown in Figures 19, 20, and 21. And, similarly. Figure 2c, an 



