The elements of embryology. / By M. Foster ... and Francis M. Balfour.

  • Michael Foster
Date:
1874
Catalogue details

Licence: Public Domain Mark

Credit: The elements of embryology. / By M. Foster ... and Francis M. Balfour. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

    272/336 (page 246)
    the embryo, both as a transparent, and as an opaque object, seen from below as well as from above. These sketches will be of great service to him when he comes to study the sections of the same embryo. On preparing sections of the embryo. Hardening. a. 'With, chromic acid. The embryo must be immersed in the way recommended under F, in a solution of the strength of '1 p. c. for 24 hours. From this it should be removed and placed in a stronger solution ('3 p. c.) for another 24 hours. If it then appears sufficiently hard, it may be at once ]Dlaced in alcohol of 70 p. c, in which it should remain for one day, and then be transferred to alcohol of 90 p. c, after remaining in which for two days, it should lastly be placed in absolute • alcohol; in this it can stay till required for section. If the chromic acid has not by this time been com- pletely got rid of, the absolute alcohol must be changed, till the specimen is entirely free from acid. h. With picric acid. The best form for applying the picric aeid, is that introduced by Dr Kleinenberg. With 100 parts of water, make a cold saturated solution of picric acid; add to this two parts of concentrated sulphuric acid: filter and add to the ■ filtrate three times its bulk of water. In this solution of picric acid, the embryo must be immersed in the same manner as when chromic acid is used {vide F). After remain- ing in the acid for Jive hours, it is to be treated successively with weak, strong and absolute alco- hol, as was done in the case of the chromic acid. Still more difficulty will probably be found in getting rid of the picric acid, than was found to