On the Embryogeny of Hippuris vulgaris. 259 
fortunate enough, on a visit to Paris, to make the acquaintance 
of the ingenious inventor of the aneroid—which I find, in its 
present state, he regards as a domestic rather than a scientific 
instrument, —an estimate of its capabilities in which its continued 
use leads me very much to concur. Still, while I find it per- 
fectly well adapted to the house purposes of a common weather- 
glass, I can say no less of it as an instrument for taking heights, 
than that it is far more commodious and much less likely to get 
out of order than a mercurial barometer—and when limited, as 
my trials were, to heights not exceeding 12U0 feet, that it 
exhibits quite sufficient accuracy for general purposes—a Nad 
which I have no doubt in its present form may be extended to 
heights of some 2500, and were the index graduated to 24 or 25 
inches of the mercurial barometer, probably to the height of any 
hills in Great Britain. 
M. Vidi, however, has made some elaborate trials towards a 
more purely scientific instrument. If he persevere, I have no 
doubt he will succeed. 
The grand Exhibition of Works of Art in London in 1851, 
offers him a good opportunity for submitting his invention to more 
general notice,—and, to the judges perhaps, a not inappropriate 
object for a premium.—W. H. H. 
XXV.—On the Embryogeny of Hippuris vulgaris. By Joun 
Scorr Sanperson, F.B.S.E., Member of the Royal Medical 
Society of Edinburgh*. 
Tue subject of the origin and development of the embryo has 
been lately brought before botanical readers so frequently in the 
various journals appropriated to vegetable physiology, and so 
much has been done by so many observers in the elucidation 
of the subject, that it must appear somewhat uncalled for to 
occupy your time with facts and observations which are only re- 
petitions of what has been much better detailed by others in 
regard to other species, and by which therefore these results can 
only be corroborated. 
As however the observations referred to are contained in foreign 
journals, and may have escaped the notice of many members 
whose attention has not been directed to this particular branch 
of botanical science, I trust that the following details will not 
prove wholly unacceptable, more especially as they will enable 
me to lay before you some of those highly important generaliza- 
tions, which are to be obtained from the splendid researches of 
Hofmeister, Unger, Tulasne, and others, on the subject of em- 
* Read before the Botanical Society of Edinburgh, Feb. 14, 1850. . 
7* 
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