52 BULLETIN OF THE 
in successive generations ,beyond the seventh increases more and more 
slowly, and finally decreases to zero. Thus the average rate of increase 
of individuals in the generations 7 to 10 over those in the preceding is 
only 16%. 
One finds here, as elsewhere, that the number of individuals cut by 
any unit of arc, the primary individual being taken as a centre, remains 
practically constant, whatever the radius of the arc. 
In studying the creeping stocks of Cheilostomes (Plate VITI. Fig. 71), 
young corms have been chosen because they exhibit fewer irregularities 
of formation than old ones. Such irregularities are chiefly due to some 
unevenness of the surface on which the corms lie, but sometimes 
apparently to a crowding of individuals. Old rows of individuals are 
occasionally entirely cut off and end in the middle of the stock; some- 
times two rows running side by side, perhaps derived from a common 
ancestor, suddenly merge into one again. In one case, Escharella varia- 
bilis, Verrill, I have seen three rows thus merge into one at the margin, 
suggesting the existence of a samknopp (common bud) in the sense of 
Smitt (65, pp. 5-16). Ostroumoff (86%, pp. 338, 339) has observed 
a case in Lepralia Pallasiana. He says: “Dans quelques cas, qu’on 
peut considérer comme des anomalies, il arrive parfois que deux bour- 
geons, provenant de loges différentes, viennent a se fusionner.” It seems 
to me, therefore, that while Nitsche (’71, pp. 445, 446), who opposed 
with such vehemence and success the idea of Smitt that zocecia arise from 
an undivided marginal zone of cells, was quite right in affirming (71, 
p. 447) that even the smallest marginal zowcia are sharply marked off 
from the adjacent ones, yet he overlooked the possibility that under 
certain circumstances the lateral walls might fail to develop, and thus 
one zoocium might arise in the place of two, or even three. 
I have not read Smitt’s Swedish paper, but I do not find anything 
in the translation given by Nitsche to warrant the latter’s conclusion 
(71, p. 446) that Smitt believed the “ Gesammtknospe ” to be “ formed 
from the sum total of the mature peripheral zoccia.” If I understand 
Smitt, he conceived the samknopp not to be derived from the most 
peripheral mature zoœcia, but to be self-proliferating, and to give rise 
to the rows of zomeia, not to arise from them. It is the “bud of 
the colony,” not the sum of the buds of the peripheral individuals of the 
stock. In this I would agree with him exactly. Although usually one 
finds the marginal gemmiparous tissue forming the lateral walls at the 
extreme edge of the corm, and thus apparently separated into wholly 
distinct adjacent gemmiparous masses; under certain conditions, the 
