212 THE AMERICAN MONTHLY [September, 



Wliat is a Species in the Diatoniaceae ? 



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 Diatomaceaj any more than, we acknowledge with 

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

 thoughts were brought up by studying the Diatomacese. And to 

 study of the Diatomaceae they must be collected from everywhere, 

 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, 186S, 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 

 Schizo7iemas and Hojmxocladias are but forms of two species. 

 Last Sunday morning (22nd) I collected on the shore at Staten 

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

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

 Schizonema Grcvilleii^ and apparently a small form like a small 

 Schizonema with parallel sides to the frustule. I mounted some 

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

 o7icma Gi-evilleii 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 Schizonei7ia which I have 

 called Grevilleii and a small Homceocladla in the same tubes ; 

 the Schizone7na is the commonest. Since then (April 21) I have 

 made gatherings at Hell Gate, foot of 5Sth street, and find the 

 rocks covered with Schizo7ie77ia 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 Schizofie77ia 

 as at Staten Island with the small form with it in the same tube. 

 I also find, but rarer, Schlzo7ic77ia G7'evi/len and S. crticiger 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 iMay, I find Schizo7ie77ia C7-uciger 

 and Nitzschia closte7-iu77i both together in the same tube." April, 

 1S87, is a memorandum that "on an oyster scow at Oakland, 

 California, there is Schizo7te77ia G7-eviIleii and a Ho77iceocladia 

 both in the same tube." 



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



