l886.] NEW-YORK MICROSCOPICAL SOCIETY. 161 



rare. Many of the Naviculce were in pairs, as if in conjunction. 

 This fact made it possible to measure two at a time, which was 

 done in quite a number of cases, with the surprising result that 

 the pairs were all of exactly the same size. Some of these 

 thus in opposition presented their sides to view, and some their 

 fronts, thus enabling me to get the three dimensions, and the 

 result showed entire uniformity of size, namely, length WirTy in., 

 thickness Wutt in., and width Ta^TTij in. Could such remarkable 

 agreement mean that these diatoms had all attained their full 

 size, or could it mean arrest of growth at a certain point con- 

 sequent upon exhaustion of pabulum ? Hence arose a necessity 

 for an analysis of the waters. 



Jar Z>, into which was put the water that had been filtered 

 and afterwards boiled, was next examined. It did not contain 

 one diatom. The deposit in it was composed entirely of con- 

 fervse, the germs of which had entered from the air during the 

 two weeks of exposure mentioned. This showed that the at- 

 mosphere had nothing to do with sowing diatom spores in my 

 jars. Also, it proved in this case, that diatom seed could not 

 survive the temperature of boiling water, though possessing a 

 viability which survived an arrest or abeyance of the life-force 

 through sixteen years of inertness in total darkness True it is, 

 that the silicate frustules or skeletons of diatoms are found in the 

 hot springs or geysers of the West, in waters of temperatures 

 varying from 140° to 200° F. ; but not a living diatom has been 

 found therein, and, from our experiment just described, we 

 must believe that none living ever will be found. 



With large expectations I next examined jar E, the last of the 

 series. During the course of these discoveries, I felt sure that 

 the last experiment would be, like the last wine at the feast, 

 the best, the most satisfactory. In this jar E had been rinsed 

 the filter papers used in filtering three jars of water, and from 

 such a generous sowing what might I not expect ! Strange to 

 say, the first dip of the sediment in the bottom yielded nothing 

 but unicelled algae. So did the second, and the third, and 

 others that I made, until my disappointment at such unex- 

 pected results amounted to chagrin. Only an accasional Navi- 

 cula was found, and still more rarely a forlorn Amphora ; never- 

 theless, the great number of confervge showed that good grow- 

 ing conditions were present in the jar. The few diatoms seen 



