MUSEUM OF COMPARATIVE ZOOLOGY. an 
primary polypides, or rather the primary and secondary one. Moreover, 
as the series of sections shows, the stolon does not exist merely in this 
section, but it isa disk which is cut here in one of its diameters. A sepa- 
ration of the stolonic mass has occurred between the two oldest polypides, 
so that the ectoderm is here in contact with the coolomic epithelium, 
just as is the case between buds in the adult stock. As the colony in- 
creases, the inner and outer margins of the stolonic tissue continue to 
extend farther outward, and this tissue forms at first a broad ring of 
ever increasing diameter. Later, as the area of the stock increases, the 
ring becomes broken, so that, instead of growing along an infinite number 
of radii, its growth is confined to a few, as in the adult colony, 
I will defer a discussion of the significance of these facts to the gen- 
eral part of this paper. 
B. GENERAL CONSIDERATIONS. 
I. Laws of Budding. 
Carefully conducted studies on stock building have generally revealed, 
just as these on Bryozoa have shown, a law in budding. This law in 
budding results in the formation of a stock the interrelation of whose 
individuals is a determinate one. I now propose to offer an hypothesis 
to account for the existence of these laws, and then to show how facts 
of budding in Bryozoa and other groups can be explained by means 
of it. 
And first of all I must acknowledge that this hypothesis, although 
perhaps here first formulated, really depends upon observations and de- 
ductions made long ago on this group, first by Hatschek, who from 1877 
has maintained that individuals do not arise independently of one an- 
other, and secondly and mostly to Braem, who in ’88 (pp. 505, 506) 
declared of Phylactolamata “dass in dem Stock keine Knospe entsteht, 
die nicht auf das embryonale, d. h. den specifischen Leistungen der 
Körperwand noch nicht angepasste Zellmaterial einer älteren Knospen- 
anlage zuriickgienge und dass somit in der ersten Knospe des keimen- 
den Statoblasten sämmtliche Knospen des künftigen Stockes implicite 
enthalten sind.” Not less is the following hypothesis indebted to the 
ideas of Roux and Fraisse, and to Nussbaum, who has said (’87, p. 
293): “ Ein lebendes Wesen ist somit als Ganzes oder in seinen Theilen 
soweit individualisirt und vergänglich, als die Gewebebildung und die 
Theilung der Arbeit vorgeschritten ist; das Ueberdauern der Einzelexis- 
