44 SCIENCE PROGRESS 



general and comparative survey; "Actinian Behaviour" 

 (ibid. Feb. 191 7). The animals represent a low grade of organ- 

 isation as might be expected, and a certain amount of indepen- 

 dence of the parts render the " organic unity of the animal as 

 a whole " very weak. In the taking in of food, for example, 

 several parts are involved, but it is only the neuro-muscular 

 apparatus of the tentacles whose activity affects the action of 

 the animal as a whole, the other parts being to a considerable 

 degree independent. The entire evidence bears out this, and 

 the author concludes that " Actinians exhibit only a low 

 degree of organic unity which is shown at its highest in their 

 locomotion. They are organically more nearly a sum of parts 

 than a unit. 



Other papers include : " On a Larval Actinian Parasitic 

 in a Rhizostome," by Badham (Quart. Jour. Micro. Sci. vol. 

 lxii. Feb. 191 7) ; " Observations on the Influence of Salt and 

 other Agents in modifying the Larval Development of the 

 Hookworms, Ankylostoma duodenale and Necator Americanus," 

 by Nicoll (Parasitology, vol. ix. Feb. 191 7) ; " On the Develop- 

 ment of Ascaris lumbricoides Linn, and Ascaris suilla Dug. in 

 the Rat and Mouse," by Stewart (ibid.) ; " Sclerostome Para- 

 sites of the Horse in England, II. — New Species of the Genus 

 Cylichnostomum," by C. L. Boulenger (ibid.) ; " On the 

 Nervous System and other Points in the Structure of Owenia 

 and Myriochele," by MTntosh (Ann. and Mag. Nat. Hist. 

 March 191 7) ; and ; ' On the Scolex in the Cestode Genus 

 Duthiersia and on the Species of that Genus," by Beddard (Proc. 

 Zool. Soc. Feb. 191 7). 



" A Cytological Study of Artificial Parthenogenesis in 

 Cumingia," by Morris (Jour. Exp. Zool. vol. xxii. Jan. 191 7), 

 throws considerable light on the phenomenon dealt with. 

 The eggs can be made to develop parthenogenetically by 

 exposing to certain temperatures and then to hypertonic 

 sea-water. The nearest approach to normal development 

 occurs in eggs that do not form polar bodies, and it is in- 

 teresting to find that in these cases the two nuclei formed 

 from the first polar spindle reunite to form a cleavage nucleus. 

 The same may happen, but does not do so frequently, with the 

 second polar spindle. No sign of normal development is ex- 

 hibited by eggs that have given off two polar bodies. Conklin 

 has investigated the " Effects of Centrifrugal Force on the 



