Generally Botrylloides violaceum propagates by palleal budding alone. Only when a small piece of a colony devoid of zooids is isolated, new buds are formed from the walls of the test vessels, i.e., vascular budding appears. As in Botryllus, these new buds are formed from aggregations of lymphocytes under the wall of the test vessels. Unlike Botryllus, the buds are not bound to any definite sites, but are distributed irregularly along the walls of the vascular system. The buds generally appear 2-3 days after isolation, at whatever phase of the original colony the isolation may occur. Major difference between Botryllus and Botrylloides is that in the former vascular budding coexists with palleal budding, while in the latter vascular budding is totally suppressed in the normal life of the colony.