On the Embryogeny o/'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 1.200 feet, that it 

 exhibits quite sufficient accuracy for general purposes— a power 

 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 John 

 Scott Sanderson, F.B.S.E., Member of the Royal Medical 

 Society of Edinburgh*. 



The 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- 



* Bead before the Botanical Society of Edinburgh, Feb. 14, 1850. 



17* 



