EECENT RESEARCHES OK THE RA.DIOLARIA. 183 



transition from unicellular to multicellular organisms. Hertwig's 

 view does, in fact, seem to be, as he says it is, the old view, that 

 the nucleolus divides first, and then the nucleus. In support he 

 refers to the labours of Carter, Wallich, Grreef, Claparede, and 

 Laehmann, as showing that in the nucleus of E-hizopods nume- 

 rous nucleoli develop themselves, which pass out from the nu- 

 cleus and grow in the surrounding protoplasm into Amcebiform 

 bodies with a nucleus and contractile vacuoles. He also refers 

 to Auerbach's multinucleolate nuclei in the tissues of Dipterous 

 larvse about to assume the pupa condition. 



To conclude, the multicellular nature of Eadiolarians now de- 

 pends entirely on the normal nature of their yellow cells, and on the 

 correctness of the observations as to the centripetal cell-groups 

 of PTiysemcttium. 



As has been said, neither of these phenomena can be reposed 

 on as being certainly of the nature of true cells forming part of 

 the normal organization of the Eadiolarians in which they have 

 been found ; but even if they are so, and if we are compelled 

 therefore to regard Eadiolarians as multicellular, their multicel- 

 lularity is of a radically different kind from that of any of the 

 Metazoa, and none of their parts, whether truly cells or not, have 

 any valid claim to the denomination of a tissue. 



Literature. 



In the great work of Professor Haeckel, ' Die Eadiolarien,' will 

 be found complete and ample references to all the literature of 

 the Eadiolaria antecedent to its publication. Since its appear- 

 ance the following publications, relating to these animals, have 

 appeared. 



Ehrenbeeg. Abhandlungen der konig. Akad. der Berlin, 

 1862, pp. 39-74, pis. i.-iii. ; 1868, pp. 1-55 ; 1869, pp. 1-66, pis. 

 i.-iii. ; 1870, pp. 1-74, pis. i.-iii. ; 1871, pp. 1-150, pis. i. & ii. ; 

 1872, pp. 131-400, pis. i.-xii. ; 1875, pp. 1-225, pis. i.-xxx. 



(These papers contain notices, with or without figures, on dif- 

 ferent Eadiolarians, with observations on their distribution in 

 time and space.) 



Ernst Haeckel. Zeitschrift fUr wissenschaft. Zoologie, vol. 

 XV. p. 342, pi. xxvi., 1865. 



(A memoir on the sarcode of Ehizopods, with special references 

 to many Eadiolaria, and with descriptions and figures of the new 



