20 J. S. DUNKERLY ON OUR PRESENT 



of the group. He was interested in J. Clark's description of 

 them, and at once started to look for Choanoflagellates. In his 

 Manual of the Infusoria (1880-82) he gives an account of several 

 new genera and many new species. Some of the latter are 

 exceedingly doubtful, as he gives different specific names to forms 

 which, from his own figures, appear to be identical. However, 

 he seems to have seen more of, and certainly more in, the 

 Choanoflagellata than any other observer. He had the good 

 fortune to be able to use some very high-power objectives of 

 Powell and Lealand, including a ^V'. Many of his specimens 

 came from aquaria, either marine or fresh-water, at Brighton, 

 Hastings and even the Crystal Palace. Biitschli, in his Protozoa 

 (1883-87), added little to Saville Kent's account of the group. 



The next investigator to devote special attention to the group 

 was R. France, of Hungary. He published in 1897 a monograph 

 of the Choanoflagellata, or Craspedomonadina, as he styled them, 

 with a valuable historical and critical account of the group. He 

 wisely revised Saville Kent's specific nomenclature, recognising 

 that the different varieties must be classed under general forms 

 or types rather than as separate species. 



Fisch, a professor of botany, described division and the forma- 

 tion of swarm-spores, in C odonosiga botri/tis, in a very interesting 

 paper published in 1885. A few isolated papers have contained 

 descriptions of new species, but our knowledge of the structure 

 and affinities of these collared monads is still very incomplete. 



A typical Choanoflagellate is seen in PI. I., Fig. 1. It has an 

 oval, naked protoplasmic body with a nucleus, one or two con- 

 tractile vacuoles, and a single flagellum arising from a basal 

 granule or blepharoplast, which stains deeply in prepared speci- 

 mens. Surrounding the base of the flagellum is the characteristic 

 collar, a protoplasmic membrane, cylindrical or basin-shaped. 

 The whole body is motionless, except when shaken by the violent 

 movements of tl.e flagellum, the latter being in constant move- 

 ment either along its whole length or especially at the tip. 



