l886.] NEW-YORK MICROSCOPICAL SOCIETY. 163 



the plate, they measured respectively -sh-s by W^ff, zhu by tsists and 

 TifT by iTrj7(T. 



It is with regret that I allow this paper to go to press without 

 containing a full determination of the species of the diatoms 

 spoken of. For this determination I had depended upon Prof. 

 H. L. Smith, but the serious accident which befel that eminent 

 diatomist made it impossible for him to furnish the list. 



RESUME. 



1. My experiment of December, 1882, the results of which I 

 have confirmed by so many observations made since, demon- 

 strates that diatoms originate in spores, or seed-like bodies. 



2. These spores are exceedingly minute, passing easily 

 through filter-paper. 



3. They are probably resting spores not motile, and may be 

 held in suspension awhile like the mineral matter in turbid 

 water. 



4. The viability of these spores is remarkable. The dia- 

 toms raised in the first series of experiments were from spores 

 whose life-force had lain dormant in total darkness for thirteen 

 or fourteen years ; those in the second series, for sixteen years. 



5. The viability of some genera is greater than that of others. 

 This is notable of Navicula in these experiments, and is conso- 

 nant with the numerical lead of this genus in forms or so-called 

 species. 



6. Owing to the environment becoming abnormal, develop- 

 ment may be rapid and erratic to a surprising degree, but upon 

 aberrant and asymmetrical lines. Suppressed at some points, the 

 life-energy is precociously active at others. 



7. Diatoms have embryonal stages or forms, with silicate 

 fronds. 



8. As to kind and quantity, the crops are capricious and vary 

 without apparent reasons. 



9. As to the parentage or begetters of the spores in my ex- 

 periments: They were not generated in the vessel which con- 

 tained the water, but were begotten of sporangial mother cells in 

 the Bay. 



ANALYSIS OF THE WATER. j 



The fact that in one crop the diatoms of one species were all of 

 the same size, caused me to supect that they had ceased to grow 



