VASCULAR BUDDING, A NEW TYPE OF BUDDING IN BOTRYLLUS

¹ Zoological Institute, Tokyo Kyoiku University, Tokyo, Japan

1. In Botryllus primigenus, it has been found that, in addition to palleal budding, new buds are formed also from aggregations of blood-cells at the base of ampullae.

2. The blood-cells partaking in the formation of buds are lymphocytes as defined by Sabbadin.

3. The formation of buds is possible only at a certain phase in the developmental cycle of the colony.

4. Even then, the buds are formed, not on all ampullae, but only on those lying in the most vigorously growing edges of the colony.

5. Our discovery is of significance in the following three points:

a. The ability to form new buds from the vascular wall has not completely disappeared in Stolidobranchiata.

b. A species can propagate by two entirely different kinds of budding. In our case, one is ectodermic-palleal and one mesoblastic-vascular.

c. The lymphocytes are themselves capable of organizing new individuals.

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