19 



NOTE ON OUR PRESENT KNOWLEDGE OF THE 

 CHOANOFLAGELLATA. 



By J. H. DUNKERLY, B.Sc. 



(Bead Novemher 2ZTd, 1909.) 



The Choanoflagellates are a group of the Protozoa which have 

 been rather neglected by microscopists. This neglect is due to 

 more than one cause. They are very minute organisms, requiring 

 high powers for their study ; they are not parasitic ; and they 

 are not usually motile. Some one or all of these causes may 

 account for the fact that although these Choanoflagellates were 

 discovered over forty years ago, yet few microscopical workers 

 are familiar with them. 



They were first recorded accurately by James Clark, of 

 America, in 1867, although previous workers may have seen 

 them ; EpisttjUs hotrytis of Ehrenberg probably being identical 

 with what is now known as Codonosiga hotrytis. Stein, in his 

 wonderful monograph on the Infusoria, says that, although he 

 had worked many years at Infusoria, he had never seen a collared 

 flasjellate until after readinor J, Clark's account of them. He 

 then remembered having previously seen the empty cases or 

 loricae of Salpingoeca, and before a year had passed he found 

 many specimens of Choanoflagellates, including one or two new 

 species. We all know in microscopy how much easier it is to 

 iind anything when we know that it is there to be found; 

 unfortunately this in some cases leads to wilful interpretation 

 in accordance with preconceived notions. Although Stein had 

 investigated the Choanoflagellata as early as 1867, he did not 

 publish the greater part of his figures until 1874. To Saville 

 Kent belongs the credit of publishing the first systematic account 



