256 BOTANICAL GAZETTE. 
flat, abruptly acute. I have found it rising to the surface in still 
ponds, in water 4 to 6 feet deep! Sterile plants only seen. 
Eastern Mass. Also collected by L. H. Bailey, Jr., in Mich., 
and C. Wright, in Texas. : 
Naras Micropon, A.’Braun.—Sheaths and teeth similar to 
those of N. flewilis, with which it was formerly classed by Braun, 
except that the teeth are very minute and sometimes very numer- 
ous (30-100): leaves less than 1mm. broad, 5 to 8mm, long, 
somewhat recurved, undulate, not revolute. The species is mainly 
characterized by its fruit, which is very short (1 to 2mm.), sculp- 
tured on the surface by 16 to 20 rows of nearly square reticula- 
tions, and scarcely shining. The fruit of NV. flerilis is 24 to 3mm. 
in length, conspicuously smooth and shining, especially in the 
denuded nutlet, the superficial marking indistinct in mature 
fruit, but consisting of about 40 rows of roundish-square or it- 
regular shallow reticulations. 
Perdinales river, Texas, coll. Lindheimer, 1847. 
By the courtesy of the curator of the Chapman Herb. at Co- 
lumbia College, Prof, N. L. Britton, I have been permitted to 
see the original specimen of Chapman’s N, flevilis, var.? Fusifor- 
mis, and I fully agree with Braun that it is N. microdon, so that 
our localities for this species in N. America must include Flor- 
ida. Our form of the species is classed by Braun as N. miecro- 
don, var. Guadalupensis, it having been originally collected by 
Duchassaing at the French West India Island Guadaloupe. 
Biology of the Conjugate. 
BY WM. TRELEASE. 
€ common Brook-Silks (Spirogyra and Zygnema) have 
served an excellent purpose in the biological laboratory beeausé 
of the large size of their cells, and the distinctness with which 
the parts of the latter stand out; and the completeness of their 
reproductive processes, which can be followed even by students 
who have had little training in laboratory manipulations. Yet 
the details of their vital processes, and even of their structure, 
are known to comparatively few who use them, and the state 
ments concerning both are scattered through isolated panes. 
recent publication, by Strasburger, Schmitz, and. others, whie 
are still inaccessible to most teachers. Bringing the most impor 
