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CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



Text-Fig. 3. 

 Fig. 3. The same as fig. 2 but seventeen hours later. Letters and figures refer to 

 the same ampullae. The arrow indicates a place where blood was seen to pass from the 

 stalk of ampulla 5 into ampulla a. The case of ampulla a shows better than any other 

 how an ampulla may be in contact with other ampullae for a long time without fusing 

 but fuses with a vessel as soon as it meets it. On the left of figs. 2 and 3 several stages 

 in the process of the reduction of fused ampullae to make normal blood-vessels may be 

 observed. Camera; x 43. 



It seems probable that the tests of the two colonies must 

 have fused before the ampullee can pass the boundary of 

 their own colony; but the test is so transparent that it very 

 frequently happens that no boundary line can be detected 

 between two adjacent colonies that are not in the process 

 of fusing. After two colonies have become thoroughly 

 united, however, one is not able to see any boundary line 

 between them. It is therefore certain \.\\2it fusion does occur 

 between the tests of two colonies. 



6. Physiological Characteristics of Fused 

 Colonies. 

 We have seen that so far as several morphological char- 

 acters are concerned, fused colonies are exactly the same 

 as a single colony. They are united in a single mass, they 

 are contained in the same test, and they have a single vas- 

 cular system. But, associated with these morphological 



