214 GEO - W - TANNREUTHER. 



secrete a sticky substance before the bud becomes separated from 

 the parent. 



The first step in the process of separation of bud from parent 

 occurs in the mesoglea. Fig. 8 represents the condition of meso- 

 glea and cells before separation begins. The mesoglea, which 

 connects the bud with parent, is uniform throughout. But almost 

 immediately it becomes thinner and thinner until it is indistin- 

 guishable from the ordinary cell wall (Fig. 9, a). The enteron 

 leading from the parent to the bud becomes discontinuous by the 

 union of the endodermal cells. New mesoglea is now formed at 

 the extreme basal end of the bud (Fig. 9, b} and at the point of 

 former union with the parent at c. The mesoglea, which is more 

 of a gelatinous nature, increases in thickness "by means of secre- 

 tion from the endodermal cells and soon reaches its normal con- 

 dition (Fig. 10, b and c). After the formation of the mesoglea 

 is complete, the bud remains attached to the parent by a few ecto- 

 dermal and endodermal cells, as shown in Fig. 10. The former 

 connecting mesoglea is represented by the dotted lines at a. The 

 cells between the dotted lines, which are endodermal, become 

 external to the newly formed mesoglea and take the position of 

 ectoderm. Whether these cells persist or not and function as 

 ectoderm is difficult to say, as there is no possible means of fol- 

 lowing them in the process of separation of bud from parent. 



SUMMARY. 



1. The initial step in the formation of bud in hydra is found in 

 the interstitial cells. 



2. The most active region of growth in the formation of the 

 bud is found at the junction of the forming bud and parent, where 

 the cells divide very rapidly and contribute almost entirely to its 

 growth. 



3. When the bud is nearly formed the ectodermal cells in the 

 basal region become transformed into granular glandular cells, 

 which later secrete a glutinous substance for attachment of hydra. 



4. The rate of growth in buds is controlled by the amount of 

 food present. Starvation after buds are nearly complete often 

 causes their complete absorption by parent hydra. 



ZOOLOGICAL LABORATORY, 

 UNIVERSITY OF MISSOURI. 



