MUSEUM OF COMPAKATIVE ZOOLOGY. 73 



Braem ('90, pp. 33 and 44), Ehlers ('90, p. 9), and others, have since 

 done. I shall represent the mass of indiiferent cells by an asterisk, 

 and individuals (according to Chun's nomenclature) by the use of the 

 large and small letters of the Eoman alphabet, and, finally, by Greek 

 letters. The typical stock of Paludicella might then be graphically 

 represented thus (cf. Plate I. Figs. 2 and 2") : — 



(1) 



Here the letters indicate polypides or their Anlagen, and the asterisks 

 indiflferent tissue. The individuals I'epresented by capital letters may be 

 called primary individuals ; they may be said to belong to the primary- 

 series, and to have been derived from the primary indifferent mass. 

 The individuals repi-esented by small Roman letters will then be secon- 

 dary individuals, belonging to the secondary series and arising from sec- 

 ondary masses, etc. It is to be observed that this indifferent tissue is 

 here found only at the tips of branches or Anlage of such. No asterisks 

 are found adjacent to the adult polypides A, B, C, etc., which have 

 given rise to lateral branches, and these have therefore no power of pro- 

 ducing new parts of the colony. The asterisks must not be regarded as 

 having been descended from the letters which they adjoin, but from the 

 terminal asterisks only ; that is to say, in Paludicella embryonic tissue 

 has originated from terminal embryonic tissue, and not from indifferent 

 tissue left remaining alongside of the polypides. 



Conditions differing in an interesting manner from these were found 

 by Braem ('90, pp. 18-32) and myself (Davenport, '90, pp. 103-106) in 

 Phylactolsemata. In Plumatella Braem has shown in the clearest man- 

 ner how some of the embryonic tissue around a polypide at the proximal 



