Kansas IInivehsiti Science Bulletin. 



Vol. IV, No. 4 MARCH, 1907. 1 vJL'? xxv ''no'^^' 



SOME LABORATORY METHODS IN EMBRYOLOGY. 



BY R. G. HOSKINS. 



•'T^HIS paper is a description of some of the methods em- 

 -*- ployed in the zoology department of the University of 

 Kansas in the preparation and handling of material for 

 routine work in embryology. There is not much herein that 

 is original ; it is rather a systematic arrangement of data 

 adapted from many sources. The methods have this, how- 

 ever, to recommend them : they have all been found satisfac- 

 tory under ordinary working conditions. The material used 

 is mostly as follows : For holoblastic cleavages of the egg, 

 the frog ; for delamination and early organogenesis, the chick ; 

 and for later organogenesis, the pig. The method of prepar- 

 ing each for class use will first be given. 



Frog eggs are collected in early May, in a rather extensive 

 series of lots. From these are selected, if possible, the various 

 stages desired. If any stages are lacking, a lot of younger 

 age is kept in a dish of water exposed to bright sunlight until 

 the right stage of development is reached. They are then 

 preserved in four per cent, formalin until wanted. The 

 stages used are 1-, 2-, 4-, 8-, 32- and 128-cell, early and late 

 blastopore, and a stage showing the neural folds. 



For chick material, a satisfactory supply of eggs can usually 

 be obtained from some farmer without any special trouble. It 

 is well, however, to get them in the spring, when the vitality of 

 the eggs is strongest. These are placed in an incubator for 

 the necessary time to secure embryos of any desired age. In 

 reckoning the time to remove the eggs, one hour should be 

 allowed in addition to that required for the desired develop- 



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