ZOOLOGY AND BOTANY. MIGUOSCOPY, ETC. .33 



oomposed of two separate ossifications, the paired fins of Easthenopteron 

 being evidently the reduced archipteryg'iuiu type of Gegenbaur (uniserial 

 rather than biserial). J. A. T. 



Phylog'eny of the Orthobiont. — Charles Janet {Sur. la Phijlogemse 

 de V Orthobionte, Limoijes, 191G, 72 pp., 6 tables, <S pis.). According to 

 the author the primitive organism was a Phyto-zoo-flagellate with both 

 photosynthetic and animal modes of nutrition. This primitive organism 

 differentiated into Phyto-flagellates (holophytic), leading on to plants, 

 and Zoo-flagellates (holozoic), leading on to animals. The successive 

 generations of a flagellate include: (1) A " merism " consisting of 

 groups of monoplastid individuals enclosed in a cyst (a " blastea ") ; 

 and (2 ) a " merism " consisting of a multitude of free monoplastid 

 individuals (a " plethea "). Among the free monoplastids there is an 

 occurrence of special gametes which unite in pairs to form zygotes. 

 These multiply by bipartition. All the progeny of a given zygote 

 before fresh gametes occur constitute a " holobiont " ; a direct line 

 from one zygote to a new zygote constitutes an '' orthobiont." The 

 orthobiont of the primitive flagellate consists of an alternation of 

 encysted blasteas and sporadic pletheas, and the author's idea is that 

 the orthobiont of any organism consists of a succession of blasteas and 

 pletheas homologous to the blasteas and pletheas constituting the 

 orthobiont of the primitive flagellate. The author shows how this 

 Avorks out, as it seems to him to do, in cases like Voh'ox, Fiicus, a liver- 

 wort and an insect. The thesis is illustrated by numerous finely 

 drawn figures, indicating the supposed homologies, and by ingenious 

 comparative tables. J. A. T. 



Physiological Analysis of Behaviour. — H. B. Torey (Journ. 

 Animal Behaviour, 1916, 6, lskO-9). The behaviour of Paramecium in 

 the presence of an obstruction in its path shows a succession of motor 

 reflexes orientated with reference to the source of stimulation. Are 

 these and other precise responses that organisms make to directive 

 stimuli the outcome of selection whether of individual reactions or of 

 individuals themselves ? " On the contrary, evidence is accumulating in 

 favour of the view that organisms respond typically without trials ; that 

 what have been called, by a figure of speech, trials are actually definite 

 responses to stimuli that are neglected by the observer ; that behaviour 

 is the resultant of many stimuli of which the directive stimulus is but 

 one ; that, in fact, the tropic response is rigidly determined as to 

 direction by factors which complete analysis may be expected in all 

 cases to bring to light." J. A. T. 



Large Size of Abyssal Animals. — A. Sokolowsky {Schrifl. Zocl. 

 Stat. Biistim, 1919, 1, 15-l.s, 1 fig.). Attention is directed to the 

 tendency of abyssal animals to attain very large size, e.g. Macrocheira 

 {Ksenipfferia) ksempjferi, the giant crab which may measure 11 feet 

 from the tip of one forceps outstretched to the tip of the other. There 

 are large deep-witer fishes, like oar-fish; large Cephalopods ; and the 

 well-known hydroid Monocaulns imperator may rise to a heiglit of about 

 eight feet. Some deep-sea animals, not in themselves very large, are 



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