396 HARPER— ORGANIZATION, REPRODUCTION 



that the resuhing colonies are never circular in outline but always 

 somewhat elongated in one axis. The spinous projections are less 

 constantly radial in their position and the intercellular contacts 

 and intercellular spaces are far from what I have described above 

 as typical. Photographs of such irregular colonies still inclosed in 

 the mother vesicle are shown in Figs. 18-20. It is difficult, as noted, 

 to bring out the vesicle in a photograph. I have traced over with 

 dilute India ink the outlines of the vesicle in Figs. 18 and 20 to 

 bring out more sharply the points involved. Fig. 19 is left as 

 printed, but the faint outline of the vesicles and their papillae can 

 be made out. In Fig. 20 an edge view of a young colony in its 

 vesicle is shown. The figures show clearly enough that the long 

 axis of these irregular oblong and oval colonies lies in the long axis 

 of the mother cell. The vesicle, although gelatinous and swollen, is 

 apparently elastic and always maintains the outline of the mother 

 cell even to the retention as noted of tw^o papillae representing the 

 spinous projections. The conclusion is obvious that these unfavor- 

 ably situated colonies with reduced activity in swarming are unable 

 to achieve the typical compact circular plate form and the outline 

 of the young colony is influenced by the oblong shape of the en- 

 closing vesicle. The achievement of all the nice adjustments neces- 

 sary in making a typical least-surface figure requires more effort 

 than the cells of these weakened colonies are capable of and as a 

 result they conform more or less to the outlines of the confining 

 vesicle. Sometimes the result is a flattening of the outline of the 

 colony along one or both edges. Again the result is a more ellip- 

 soidal form. In cases of extreme weakness the colonies may be 

 rather angular (Fig. 23), conforming quite completely to the outlines 

 of the mother cell and, as Askenasy ('88) noted, sometimes not 

 escaping from it. In these extreme cases the colonies are practically 

 always irregular in all their dimensions, with the cells more or less 

 piled upon each other, so that the colony is more than one layer 

 thick. The spinous projections also tend to disappear under these 

 conditions. The effect of environment in modifying and disturbing 

 the morphogenetic processes is thus most clearly shown, and we 

 can class a whole series of such divergences from type as strictly 

 epigenetic and environmental in their origin. The shape and struc- 



