212 THE AMEHICAN MONTHLY [September, 



WliJit is a Species in the Diatoinaceae ? 



ARTHUR M. EDWARDS, M. D., 



NEWARK, N. J. 



A species is evanescent ; that is, it changes with its surround- 

 ings, and what we call a species now is not the same that we 

 called a species in times past, nor as it will be in the future. 

 What in Germany is called a species is not the same in England, 

 nor in America is it known by that name. In fact, a species does 

 not exist in the Diatomaceae any more than, we acknowledge with 

 Dr. W. B. Carpenter, it does in the Foraminifera. These 

 thoughts were brought up by studying the Diatomaceie. And to 

 study of the Diatomacege they must be collected from eyerywhere, 

 from Halifax, New York, Key West, Bahia, Montevideo, Cal- 

 lao, San Francisco, Sitka, Japan, China, Calcutta, Africa, Eng- 

 land and intermediate places, and studied at all seasons, in the 

 summer as in the winter and, above all, living and under various 

 circumstances. 



In my memorandum book, wherein I write down at the time 

 and illustrate with colored figures observations made, I find 

 under March 26, 1S6S, a record of this kind: "I have to-day 

 seen that which, although I was somewhat prepared for it, as- 

 tonished me. I have for some time suspected that the various 

 Schizoncjnas and Homceocladias are but forms of two species. 

 Last Sunday morning (32nd) I collected on the shore at Staten 

 Island, on rocks andstones near the quarantine landing, a mass 

 of matter, mostly Diatoms, as Mel. iiuDivmloides^ etc. In it is 

 Sc/iizonema Grcvilleii^ and apparently a small form like a small 

 Schizonema with parallel sides to the frustule. I mounted some 

 of the mass in glycerine-gelatine, and I see both the large Schiz- 

 onema Grevilleii and the small forms in the same tubes. Since 

 the above, I made other gatherings (March 29 and April 5 and 

 12) at the same place and found the Schizonema which I have 

 called Grevilleii and a small Hojuccocladia in the same tubes ; 

 the Schizonema is the commonest. Since then (April 21) I have 

 made gatherings at Hell Gate, foot of 58th street, and find the 

 rocks covered with Schizonema cruciger and a small form, both 

 in the same tube and both very active. When freed by force 

 from the tube they are both active. Also the large Schizonema 

 as at wStaten Island with the small foriu with it in the same tube. 

 I also find, but rarer, Schizottetna Grevilleii and S. criiciger in 

 the same tube." August 13, 1869, there is a memorandum that 

 " in a gathering I made in the ' Mill Pond,' S. W. near the R. 

 R. station, Salem, Mass., last May, I find Schizoneina cruciger 

 and Nitzschia closteriiim both together in the same tube." April, 

 1SS7, is a memorandum that " on an oyster scow at Oakland, 

 California, there is Schizonema Grevilleii and a Hotnoeocladia 

 both in the same tube." 



Now I have to record that for the last two vcars I have been 



