Experiments on Toads' eggs 



95 



by each, and in respect of one, these movements were so great as 

 to result in well marked pseudopodia. 



In Fig. 42, which is a series of drawings of three isolated cells 

 from gastrulating toads' eggs similar amoeboid changes are seen 

 and a slight approximation between two of the cells, a and 6, has 

 been effected. 



Now these changes in shape of the isolated cell indicate in 

 all probability contractility, at least that is one explanation of 

 amoeboid movement, and so show that the power to exert a pull 

 by contraction is not out of the question. 



5.30 



o o 



556 



o o 



O o 



6.9 



o 



6.13 



o 



o 



611k 



o 



o 



o 



7.30 



Fig. 41. Seven drawings of two isolated cells of a Toad's egg in the gastrulating 

 stage, drawn with a camera lucida at intervals as indicated. 



On the other hand there are movements, seen especially when 

 the preparation is first made, which cannot be ascribed to any 

 form of amoeboid activity, and as far as I can see not open to 

 explanation by contractility. 



Again, it may be that the attraction between cell and cell is 

 greater immediately after division than at a later period. One 

 reason why such movements occur more obviously immediately 

 after the preparation is made than later is probably to be sought 

 in the tendency of the isolated cells to adhere to the slide, which 



