February 2, 1922] 



NATURE 



131 



uical Research at La Jolla — both by work at 

 a off the coast of Southern California and by 

 inxestigation of the beach sands. 



The Dinoflag'ellata form an exceedingly impor- 

 tant source of the food supply of the sea both in 

 numbers and in the total mass produced. As 

 synthetic producers of carbohydrates, proteids, 

 and fats they hold high rank amongst microscopic 

 marine organisms, and in abundance they are 

 bc'cond only to the diatoms in the plankton, while 

 locally and on occasions they may far outnumber 

 them. These local massive developments are the 

 all but universal cause of the discoloured seas and 

 of the phenomena of luminescence. The present 

 monograph deals with the least-known and most 

 isive members of the group, the naked or 

 irmoured forms. 



>ne great difficulty in their investigation is the 

 reme delicacy of these organisms and their ten- 

 icy to undergo cytolysis in even a few moments' 

 )sure to light under the .microscope. They 

 unfortunately most sensitive to the action of 

 ing re-agents, and almost instantaneous distor- 

 and disruption prevent the preservation of 

 lanent preparations. The investigator is 

 refore limited to rapid and immediate observa- 

 of the freshly captured living and usually very 

 ive organisms. It is only on a coast such as 

 it of Southern California, where pure oceanic 

 ter with a rich pelagic fauna is brought within 

 few miles of a laboratory equipped like the 

 ripps Institution, that work such as that of Prof. 

 rfoid could be carried on. A specially devised 

 of the finest silk is towed for a very short time 

 [a depth of 80 metres, the catch transferred to a 

 itively large volume of water, rushed ashore in 

 fast motor-boat (30 miles an hour), and divided 

 at once for the microscopes of half-a-dozen 

 jistant observers, a surprising number of new 

 remarkable forms in exceptionally fine con- 

 tion being revealed. Ordinary methods of plank- 

 >n collection and preservation yield no traces of 

 these extremely delicate organisms. This is an 

 excellent example of new and refined methods at 

 sea, such as can be adopted only in connection 

 with a biological station, which are giving new 

 results of great scientific interest. It must not 

 be supposed, however, that all these Dino- 

 flagellates are confined to oceanic water. Some 

 are neritic, and species of Amphidinium, for ex- 

 ample, have been found in vast numbers on damp 

 beach sand at several localities in England, Cali- 

 fornia, and elsewhere. 



Many of these new unarmoured Dinoflagellates 

 are brilliantly coloured, as the beautiful plates 

 abundantly show, and some are wonderfully 

 NO. 2727, VOL. 109] 



organised and specialised for such minute proto- 

 zoa. Some possess, amongst other "organelles," 

 a complicated ocellus or " eye," with lens, pig- 

 ment mass, and sensory core, as well as a large 

 mobile tentacle, and groups of nematocysts 

 resembling those of Ccelenterata. The whole 

 group and its subdivisions and the numerous 

 genera, sub-genera, and species are discussed 

 most fully from every point of view — general 

 morphology and relations, minute structure, 

 physiology, history, and distribution. In their 

 nutrition the majority of marine unarmoured 

 Dinoflagellates are holozoic, and even some of 

 those that contain chromatophores and were 

 hitherto supposed to be holophytic are now found 

 to contain ingested foreign bodies in the cyto- 

 plasm. What is known of the life-cycles, includ- 

 ing encystment, spore formation, binary and 

 multiple fission, and possibly conjugation — and 

 the effects of parasitism in some forms — are all 

 discussed, but it is evident that much has still to 

 be discovered in regard to these matters. 



In regard to the evolution of the group, our 

 authors show that it probably arose from the 

 Cryptomonads, and the Dinoflagellata of to-day 

 represent the terminal twigs of a phylogenetic 

 branching. The attempt to find ciliate affinities 

 through the remarkable genus Polykrikos is 

 rejected as a misinterpretation. A new form, 

 Protodinifer, is regarded as bridging the gap 

 between the two main groups of Dinoflagellates, 

 the Diniferidea and the Adiniferidea, but it 

 may be pointed out that " Protodinifer " is 

 clearly identical with the Pelagorhynchus marinus 

 of Pavillard [Comptes rendus, January, 1917). 

 Amongst notable changes in the more familiar 

 classifications of the text-books are the removal of 

 Noctiluca from the Cystoflagellata and its inclu- 

 sion in the Gymnodinoidae, and the abolition of the 

 Pyrocystaceae of Murray, Apstein, West, and 

 others, as these latter organisms are now to be 

 regarded as merely phases in the life-history of 

 other Dinoflagellates. 



In addition to the nematocysts in Nematodinium 

 and Polykrikos and the ocellus in Pouchetia, etc., 

 the most remarkable further specialisation is seen 

 in the highly developed appendage or "prod,"^ 

 with protractile and retractile fibrillae, which 

 reaches its climax in the genus Erythropsls. The 

 authors, in pointing out the coelenterate resem- 

 blances of the nematocysts and the tentacle placed 

 on the edge of the sulcus or mouth, and also the 

 tendency to a multicellular condition seen in the 

 " chains " of Ceratium and the two-, four-, or 

 eight-celled " somatella " of Polykrikos, suggest 

 that " pelagic Dinoflagellata may have given rise 



