326 



Mr. E. Ray Laiikester on the 



Hiickel's Monera as Nuda and the Foraminifera as Testacea) ; 

 2. Nucleifera [emhracmg Amophou/eaj Gregari'mda, and Catal- 

 lacta) ; 3. Radiolaria or Cytopliora (embracing the Heliozoa 

 or freshwater Radiolaria, and the Radiolaria proper or marine 

 forms); 4. Infusoria (embracing the Suctoria and Ciliatay 

 excluding the so-called Flagellate Infusoria, which, it seems, 

 should be referred to the Volvocinean Alga?) ; 5. Noctilucida 

 {Noctiluca and Peridiniinn). 



We are indebted to Hiickel's monograph in the ' Jenaische 

 Zeitschrift' (and translated in 'Quart. Journ. Micr. Sci.' for 

 1869) for the knowledge of the Monera and their reproduction. 

 Prof. Ed. van Beneden, of Li^ge, has given a valuable account 

 of the development and structure of a Gregarina from the 

 lobster (Quart. Journ. Micr. Sci. 1870 & 1871), from which it 

 appears that the reproductive spheroid appears first as a cytode^ 

 and subsequently acquires a nucleolus and nucleus, whilst 

 considerable tissue-differentiation also goes on, though the uni- 

 cellular condition is maintained. The high differentiation of 

 the Ciliate Infusoria is thus no evidence against tlieir unicellular 

 character. 



The development of the Radiolaria is not properly known in 

 any case. Hiickel, in his great monograph, and more recently 

 Cienkowski (Schultze's Archiv, 1871, and Quart. Journ. Micr. 

 Sci., Oct. 1871) have given some account of the formation of 

 spores, which demonstrate the central capsule to be reproductive 

 like the nucleus in other groups. If the yellow cells should 

 prove to be parasitic, as Cienkowski suggests, then, as in 

 colonies oiMonera or Catallacta ^aW the units, with the exception 

 of the central reproductive body, would be of coordinate value. 



B. The reproductive sphe- 

 roid is at first a nucleated 

 particle of protoplasm ; in 

 some cases it develops from 

 a non-nucleated stage. In 

 many cases the nucleus dis- 

 appears before fertilization. 

 Division of the spheroid then 

 gives rise to a polyplast. By 

 the growth of this polyplast 

 either a hollow sphere boun- 

 ded by a single layer of cells 

 is produced, into which a 

 portion of its own wall be- 

 comes invaginated or tucked, 

 as by the adjustment of a 



Fiff. 4. 



ect 



Plamda formed by invag-ination of a 

 part of the wall of a polyplast with 

 central cavity. (Optical section.) 



