44 DEVELOPxMENT OF THE FROG'S EGG [Cii. IV 



to become splierical, but the wine-glass holds them together 

 and their surface-tensions cause them to assume definite rela- 

 tions to one another. When the drop is divided into two 

 equal parts, the halves, if little compressed, arrange themselves 

 as shown in Fig. 16, A, and if much compressed, as shown in 

 Fig. 16, E. 



If each drop is again divided,^ the resulting four drops 

 arrange themselves as shown in Fig. 16, B. A large central 

 cavity, similar to the segmentation-cavity of many segmenting 

 eggs, is present in the centre between the four drops. 



If the drops had been first divided unequally, we should find 

 that the smaller drop, having a stronger tendency to become 

 round, caused the region of contact of the two drops to bend 

 in toward the larger drop. If each of these two drops is 

 again divided, the four parts arrange themselves as shown in 

 Fig. 16, D. The same result is brought about if we divide 

 the drop at first equally and then each of the products un- 

 equally (Fig. 16, D). 



If we first divide a drop equally and then each of the two 

 unequally, but at different ends of each drop, as shown by the 

 dotted lines in Fig. 16, E, the resulting four drops arrange 

 themselves as shown in Fig. 16, F. Moreover, and this is a 

 point of much importance, it is a matter of indifference in 

 what direction the smaller drops are cut off. For instance, 

 if each of the first two drops is divided along the dotted lines, 

 a-«, a-a (Fig. 16, E), the result is the same as when the divi- 

 sion takes place along the line h-b, h-h. In either case the 

 drops arrange themselves as shown in Fig. 16, F. The two 

 larger drops come together at the centre of the system and 

 flatten somewhat against each other, producing a cross-line. 

 The two smaller drops are pushed out more toAvard the 

 periphery of the system. 



If we adopt the method of lettering shown in Fig. 16, B, 

 we can follow more readily the further divisions. Divid- 

 ing equally two of the four drops of Fig. 16, B, we find the 



1 In dividing the drops it is better to move the rod always from tlie centre 

 toward the periphery. The plane of the first division is indicated in the fig- 

 ures by the heavier line. 



