The buds always arise in the plane of the partition 

 wall, on the side of the stolon opposite to that which is at- 

 tached to the underlying surface; the line of attachment is, 

 therefore, parallel to and immediately beneath the lower bor- 

 der of tne partition. It will be seen further on that the 

 definitive s-agittal plane of the bud coincides with the plane 

 of the partition-wall, and hence the latter structure divides 

 the stolon into a right and left half in reference to the 

 parts of tne bud, and not into a dorsal and ventral portion, 

 as described by Kowalewsky (12), whose well-knov/n figure of 

 the P^erophora stolon is consequently misleading. Looking 

 at the lateral surface of the buds, as shown in that figure^, 

 the partition-wall would be seen from the flat side and not 

 on edge. 



The first indication of tne appearance of a bud is 

 a slight bulging out of tne ectoderm of the stolon at one 

 point, and if a transverse section be taken at this spot, it 

 will be seen that the two layers of the partition-wall have 

 spread widely apart, giving the appearance of a more or less 

 spherical vesicle. This is well shown in Pig. 7. The 

 walls of the partition are seen to be no longer composed of 

 flat cells, except on the lov/er side, that is, the side to- 

 wards the surface of attachment, but have become very much 

 thickened by active cell-multiplication. The cells, toe, of 

 the ectoderm over the thickeiied portion of the partition have 



-'■ This figure is reproduced in Korschelt and Heider's "Ent- 

 wicklungsgeschichte",page 1366 . 



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