24 



MORPHOLOGICAL DEVELOPMENT. 



result longer groups ; and in some species, a continuous thread 

 of them is thus produced. Figs. 8, 9, 11, exhibit these 

 several stages. Fig. 10 represents a Scenedesmus in which 



the individuation of the group is manifest. Instead of linear 

 aggregation, many protophytes illustrate central aggregation ; 

 as shown in Figs. 12, 13, 14, 15. Other instances are fur- 

 nished by such forms as the Gonium pectorale, Fig. 16 (a 

 being the front view, and b the edge view), and the Sarcina 

 ventriculi, Fig. 17. Further, we have that spherical mode 

 of aggregation of which the Volvox globator furnishes a 

 familiar instance. 



Thus far, however, the individuality of the secondary ag- 

 gregate is feebly pronounced: not simply in the sense that 

 it is small; but also in the sense that the individualities of 

 the primary aggregates are very little subordinated. But on 

 seeking further, we find transitions towards forms in which 

 the compound individuality is more dominant, while the 

 simple individualities are more obscured. Obscuration 



of one kind accompanies mere increase of size in the second- 

 ary aggregate. In proportion to the greater number of the 

 morphological units held together in one mass, becomes their 

 relative insignificance as individuals. We see this in the 

 irregularly-spreading lichens that form patches on rocks; 

 and in such creeping fungi as grow in films or laminae on 

 decaying wood and the bark of trees. In these cases, how- 

 ever, the integration of the component cells is of an almost 



