DAVENPOKT: PEOCESSES CONCEBNED IN ONTOGENY. 



193 



this process of localized solid growths the principal differentiations "f 

 Phanerogams occur. 



l\' b . 2. An important change of form 

 of a protoplasmic mass may occur inde- 

 pendently of growth by a rearrangement of 

 the nuclei of the mass. 



Good examples of this process are found 

 in the development of the larva of Lucer- 

 naria (Figure 27); in the development of 

 Ctenophores (K. & H., Fig. 67); and in 

 the changes of form occurring in the 

 " ectodermal basal plate " of Salpa (an 

 appareut syncytium), according to the 

 figures of Heider ('95, Abh. Sencken- 

 berg. naturf. Ges., Ed. XVIII. Figs. 32, 



40, 41). In so far as this process involves the migration of nuclei, it 

 is clearly closely related to Process I. 1. 



Fig. 21 



Fig. 28. 



Fig. 27. A, B, C, are three successive ontogenetic stages of Lucernaria. The 

 transformation from stage B (36 nuclei in the section) to stage C (33 nuclei in 

 the section) is due to a rearrangement of the nuclei. See K. & H., Fig. 49. 



Fig. 28. B, dispersal of elements of the gemmule A, which was formed, as 

 illustrated in Figure 5, by the aggregation of similar mesenchymatoue elements. 

 This process precedes the development of the gemmule into a larva, and accom- 

 panies the imbibition of water by the gemmules. After H. V. Wilson, '94, Jour, 

 of Morphol., IX., Plate XVI. 



