The microscope : and its application to vegetable anatomy and physiology / by Dr. Hermann Schacht ; edited by Frederick Currey, M. A.

Hermann Schacht

Date:: 1855

Credit: The microscope : and its application to vegetable anatomy and physiology / by Dr. Hermann Schacht ; edited by Frederick Currey, M. A. Source: Wellcome Collection.

172/230 (page 148)

$are in every case the most fiivourable }>lants with whicli to institute this most important investigation, esj)eeially those 1) lants in which tlie apex of tlje emhryo-sac does not even in a late stage become filled with cells, and where the nature of the ovuile ])ermits of an entire sejiaration of the apex of the embryo-sac. lla\ ing made many trials, I can recommend for this pui'pose Latlmea squamaria, Pedicularis i)alustris, and 2) articularly Pedicularis sylvatica. I have always been very successful with Lathra'a and the last-named ])lants. The pe- culiar construction of the ovrde itself, witli which the observer must make himself fully acquainted, is, in the plants above mentioned, particularly favourable for the investigation now under discussion, and the form of the ovule will afford a guide as to the direction in which the section must be made. The middle lamella of the ovule, when obtained in the manner ])ointed out above, must first be })laced under the compound microsco2>e, and examined on both sides with a jioAver of not less than 200 diameters. The lowest eye-jhece should alone be used in this examination. When it is thought that the section may be iinjiroved, the side of the section and the 2)articular point to be ojierated ujwn must be noted, and the lamella cut accordingly. The s])ecimen must then be again examined, and when the section is considered satisfactory, it shoidd be brought under the sim})le microseojie, with a magnifying jwwer of from 15 to 30 diameters, and the j)arenchyma smTounding the apex of the embryo-stxc removed with the needle. Although the obsei'\-er may carefully follow the above directions, it will seldom, if evei-, be jxossible, at least with Latlu’fea, to sejiarate com})letely and without injury the whole of the embryo-sac and its 2)rolongations from the sur- rounding tissue. In tracing the developement of the embryo, it is sufficient if the apex of the embiyo-sac is comjiletely sejia- rated, so that the observer may be able fully to study the relation of this apex to the jxollen-tube which has j)enetrated it; and with a little jxerseverauce and dexterity this sejiai’afion of the ajxex may generally be successfully effected. In Pedicularis and Lathra'a there will seldom be found to be any considerable j)ortiou of the iiollen-tube on the outside of the embryo-sac; it$