CHAPTER XXXIII 

 EMBRYOLOGICAL METHODS 



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

 in ordinary embryological technique * are constituted by the 

 improvements in fixation reported in the new sections on Cytology, 

 Glands, and in Imbedding (§ 124). 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 ha^matoxylin, are of no concern to embryologists. 

 For instance, amphibian embryos, such as those of Triton (^lolge) 

 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 polychromatic. For the 

 study of invertebrate embryology, the mitochondrial methods 

 open up a new field for research. 



The reliability of many of the new neurological methods (see 

 §§ 977 to 1107) 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 § 648 is a special treatment of the study of fats, the newer 

 methods for which can readily be used for embryological studies. 

 In § 666 is a section on " Glycogen, Iron and Copper, etc." In 

 § 778 is a chapter on the " Tissue Culture " methods. 

 In § 739 to § 775 is a report on " Intravital Staining." The 

 newer imbedding methods will be useful (§ 124). 



796. 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 Anura, Teleostea, Cyclostomata, Echinodermata, and 

 many Vermes and Coelenterata, 



In the case of the Amphibia, both the female and the male 

 should be laid open, and the ova should be extracted from the 

 uterus and placed in a watch-glass or dissecting dish, and treated 

 with water in which the testes, or, better, the vasa differentia, of 

 the male have been teased. 



Females of Teleostea are easily spawned by manipulating the 

 belly with a gentle pressure ; and the milt may be obtained from 



* Save the techniques of the Ross Harrison and Spemann schools, 

 which seem perhaps outside the scope of this work. — Eds, 



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