47 
remains undeveloped. The anther ceils are arranged not above 
one another as in other Lemnm, but behind one another or oblique- 
ly lateral, as had been stated before. The filaments show spiral 
vessels, especially visible in the connective. 
The ovules he finds single or in twos, (in the Detroit plant they 
were always in twos. * 
He then gives a minute account of the structure of the ovules 
and of the horizontal seed. The seeds are single, in one specimen 
only he found two immature but regularly developed seeds. In all 
the Specimens examined they were covered with epidermis, and 
therefore smooth ; but he supposes that in a later stage the epi- 
dermis disappears and then the seed might have a ribbed appear- 
ance, much like the other Lemnz in which the epidermis is more 
easily destroyed and thus the peculiar surface markings brought to 
light. The endosperm is thicker than in other Lemna—there is 
also a difference in the slit of the embryo. 
1 a systematic point of view the structure of the anthers would 
fortify the genus Spirodela, which altogether proves to be the most 
highly developed of all Lemnacex, if the second species of the ge- 
nus, Spirodela oligorrhiza, should exhibit the same character ; but 
e flowers of this are to him unknown. | 
he number of ovules proves of little importance as a generic 
character. Not only that here one as well as two occur—he has 
How also become acquainted with a form from different parts of 
Australia, which, in most respects very similar to Lemna minor, 
shows regularly two ovules, and which on that account he had for- 
merly thought to be allied to L. gibba, but which he now is inclined 
to consider distinct from both L. minor and L. gibba, and names 
. disperma. G. E.- 
_ 13, Arceuthobinm.—We have received further particulars about this 
interesting discovery. Mrs. Millington writes, Nov. 23: “It . 
Seems curious that the plant I found should be so nearly the oneI 
set out to find last April when I first saw the Nevada parasite. It — 
Sccurred to me then that something of that kind might cause the a 
unhealthy look and the decay of the Black Spruce, so well-known : 
among the Adirondacks. Almost the first Abies that I had an op- 
portunity to examine was literally covered with that curious growth, 
then quite small and without fruit. Some botanist, who has an— 
opportunity to examine the Abies balsamea, might possibly find it 
Infested with the same parasite. Many trees present the same ap- — 
ite is present.” Again, im 
pearance as the A. nigra when the parasite is ; : 
& letter dated Dee. 13th, she writes ; “I received a very interesting 
letter from Dr, Engelmann, and, to secure some winter ats Wane 
at we might study its habits more at large, I went myself to War- 
re , ty different trees, large and 
nsburg. I got specimens from ater St ‘ware infested. Groups _ 
Small. A Il the s jay Z 
bout 75 per cent of all the Y dead, and bore the peculiar 
of large treeg et high were ; Da . 
marks of the Pine Ti bie but the depth of the snow i el ee 
inches) prevented my looking farther among the A. “eagerpting Oa as 
__ Texpect to find it yet. The location is on the east side of the plank = 
Toad, two miles and a half from Warrensburg village, an nl 
