100 Sowe Al(j(r of Minnesota-Arthur. 



than to give a translation of: a j)ortion of u letter from M. Bornet, 

 of Pans, tlie most eminent authority on the«e plants, in which he 

 has kindly noted the peculiarities of the sf)ecimens forwarded by 

 Dr. Farlow and myself at various times, and whicli represent the 

 several lo(*alities of Minnesota and Towa: 



1. Lake Minnetonka, Minn., Aug. 20, 1883. Plants young; 

 tJie filaments are in abundant multiplication by hormogonia. The 

 contents of the cells are granular and opaque. There is no trace 

 of spores. It resembles a fr/o'o/>'/V;///(/, prol)ably 6r. P'txum^ yet [ 

 am not certain of it. 



2. Lake Phalen, near St. Paul, Minn.. Aug. 4, 1882. Con- 

 forms to the preceding; but its filaments are in a simple vegeta- 

 tive cpndition [i. e. not multiplying by hormogonia]. No spores. 



8. East Okoboji Lake, Iowa, July 80, 1883. On Utricularia. 

 This plant has commenced to form spores. The alga is still in- 

 sufficiently characterized, but I have no doubt that it l)elongs to 

 (Uceotrich ia Pi sum. 



4. Lake Tetonka, at Waterville, Minn., July 27, 1883. The 

 spores of this plant are nearly full grown; they are short and 

 tluck^ a.i^ in the iorm of Glwotricl{i<( Fistim that has been called 

 Rimilaria minuta. 



5. Shallow water near Lake Minnetonka, Minn , Aug, 18, 

 1883. On Naiasjtexil is. Spores well formed but longer than in 

 the preceding form. Length and thickness of the spores vary 

 much in G. Pisum. 



As their determination rests largely upon characters drawn 

 from the spores, it can readily be seen how unsatisfactory such 

 specimens are for comparison* and it is largely because such im- 

 ])erfect specimens have been used that authors have established so 

 many so-called species from the single true one. Of the above 

 specimens No. e5, having the longest spores, was composed of the 

 smallest individual masses of any that have been collected, while 

 No. 3 had the largest masses. Nos. 1 and 4 are the usual floating 

 form. 



M. Bornet adds that "the researches which you propose to 

 make on the floating Ghfotrichia of your lakes are very interest- 

 ing and instructive if you could follow the complete cycle of their 

 existence and connect them with the fixed forms from which they 

 were derived," It was with the hope of accomplishing this that 

 several jars were sent, in June, 1885, from Waterville, Minn., with 



