90 BERTRAM G. SMITH 



earthenware dishes contaming well water, in a cool cellar; a lim- 

 ited number of eggs were placed in each dish, and the water 

 changed daily. Under these conditions they developed normally. 

 During the early autumn all the laboratory work on the living egg, 

 and the preservation of material, were carried on in this cellar, 

 so that at no time were the eggs subjected to an unfavorable tem- 

 perature. The eggs were in general shielded from the light; 

 but for working purposes both direct and diffused sunlight, or 

 a Welsbach light, were used. 



On account of teaching duties observations in the field have 

 never extended quite to the time of hatching, consequently it 

 has been necessary to transport the living embryo for consider- 

 able distances. In the case of embryos taken after the closure of 

 the neural folds, material shipped in cool weather by express, in a 

 pail containing shallow water, did quite as well as material which 

 was given personal care during transportation and for which the 

 temperature was regulated with ice; in both cases the embryos 

 developed normally. Younger embryos require much greater 

 care in transportation; material in cleavage and gastrula stages 

 shipped by express has usually died or developed abnormally, 

 perhaps in the main because of untimely warm weather; all such 

 material was discarded. Material kept in the laboratory thrives 

 in shallow dishes containing well water, the dishes being partly 

 immersed in cool running water; no artificial a,eration is neces- 

 sary. As a check on possible abnormalities in material that has 

 been transported, I have had a series of late stages preserved from 

 material kept without transportation. 



B. FIXATION AND PRESERVATION OF MATERIAL 



The envelopes may be removed in any stage without much 

 difficulty, by means of scissors. This is very easily done after 

 the eggs have been in water for several days, since the envelopes 

 become inflated. For earlier stages, more care is necessary. 

 Eggs from the uterus, and fertilization stages, may be handled 

 more rapidly by fixing in Solution B (see below) before the 

 removal of the envelopes; they may be preserved thus in formalin, 

 but not in alcohol. After fixation the envelopes become brittle 



