CHAPTER XXV. 



EMBRYOLOGICAL METHODS.* 



577. New Advances. In nearly every case the newest advances 

 in ordinary embryological technique are constituted by the improve- 

 ments in fixation reported in the new sections on Cytology ( 681). 

 It would be a great mistake for observers to consider that fixation 

 and staining methods, such as those of Champy-Kull, Kopsch, or 

 Flemming-without-acetic acid, and iron hsematoxylin, are of no 

 concern to embryologists. For instance, amphibian embryos, such 

 as those of Triton (Molge) prepared by Champy-Kull's method are 

 extremely beautiful and instructive for study, for not only does one 

 procure cytological perfection, but also a staining which is poly- 

 chromatic. For the study of invertebrate embryology, the mito- 

 chondrial methods open up a new field for research. 



The reliability of many of the new neurological methods (see 

 865 to 921) has been brought to a state which should now induce 

 embryologists to devote even rare material for preparation, and to 

 use the neurological methods much more widely than at present is 

 the case. 



In 768 is a special treatment of the study of fats and lipoids, 

 which can readily be used for embryological studies. In 646 is 

 a section on " Glycogen," and in 650 one on " Iron and Copper." 

 In 10351045 is a Chapter on the " Tissue Culture " methods. 

 In various parts of the book further notes on intra vital staining 

 have been inserted. 



578. Artificial Fecundation. This practice, which affords the 

 readiest means of obtaining the early stages of development of many 

 animals, may be very easily carried out in the case of the amphibia 



* The sections in this chapter treating of Mammalia, Aves, and Pisces, 

 closely follow the Traite des Methodes Techniques, LEE et HENNEGUY, 

 and are due almost entirely to HENNEGUY. The corresponding parts 

 of the Grundzuge, LEE and MAYER, are taken from this work, and there- 

 fore also due to HENNEGUY, which Dr. Lee regrets to observe has not 

 always been understood, though duly pointed out in the Preface to the 

 first edition of the Grundzuge. This foot-note doss not apply to any 

 new material introduced into the present edition (J. B. G.). 



