246 THE EMBRYOLOGY OF THE HONEY BEE 



A strong colony was shaken on eight full frames of foundation 

 and two empty combs, which were placed in the center of the hive. 

 The two combs were after two hours usually found to contain 

 a fair number of eggs. These combs were then marked and 

 placed in the second story of another strong colony, above a 

 queen excluder, combs of brood being taken from the first 

 story and placed on each side of the combs containing eggs, 

 in order to make sure that these would not be deserted. After 

 the proper interval the eggs were removed from the comb, 

 fixed, and afterwards stained and mounted for examination. 

 This method is open to the serious objection of being very 

 demoralizing to the colony subjected to it, and cannot safely 

 be tried more than once on the same colony unless a con- 

 siderable interval elapses between trials. 



The data in regard to the rate of development, obtained by the 

 foregoing methods is summarized in the accompanying table. 

 This shows the approximate time in hours in the left hand 

 column, the principal development changes observed at this 

 age in the middle column, and the corresponding illustration 

 in the right hand column. 



Recorded data relating to this subject are scarce. The follow- 

 ing may be gleaned from Dickel's paper (1904). At twenty hours 

 the blastoderm is completely formed, and its nuclei arranged in a 

 single layer ( Fig. 1 ) . According to the writer's data the nuclei 

 do not become arranged in a single layer until a few hours later. 

 An egg twenty-four hours old is shown in figure 2. In this the gap 

 between the dorsal and ventral blastoderm, located just dorsad of 

 the cephalic pole, is plainly shown, as is also the case in figure 3, 

 which is about twenty-six hours old. In the figure last mentioned 

 secondary yolk cells are evident, distinguishable by their lack of 

 cytoplasm. These two figures of Dickel agree fairly well with 

 figure 16 of the present paper, representing a sagittal section 

 through an egg twenty-four to twenty-six hours old. Dickel's 

 figure 10 represents an egg thirty-five hours old in which "the 

 three germ layers are differentiated.'' It apparently corresponds 

 to Stage V or VI, although the cephalic fold of the amnion is 

 not represented. This would agree with the data in the table 

 given below. 



