280 ANNUAL OF SCIENTIFIC DISCOVERY. 



M. Babinet, inclines the ' water-courses to the right, M. Musset 

 thinks that this continuous, long-enduring, though feeble action 

 exerts the same influence upon trees ; it is best seen in trees with 

 smooth bark. 



Muscular Force of Insects. According to M. Felix Plateau, in 

 the same group of insects, the force varies inversely to the 

 weight ; that is, of two insects belonging to the same group the 

 smaller presents the greatest strength. The phytophagous fami- 

 lies appear to exceed all the others in traction force, their muscu- 

 lar strength being explained partly by the large size of the pos- 

 terior femora and partly by their small weight. As regards 

 flight, the mean forces of insects are also in inverse proportion to 

 the weights, but not to the same extent as in traction or pushing 

 force. 



Structure and Affinities of Lepidodendron and Catamites. Mr. 

 Carruthers, in the " Journal of Botany," gives his reasons for re- 

 garding these plants as cryptogams, more highly organized than 

 any existing members of the class, and for considering merely 

 analogical the arrangement of their tissues as in certain Cadacece 

 and Cycadece. He cautions geologists not to take it for granted 

 that the known conditions of the living species of a genus are true 

 also of the fossil members of the same genus, citing the case of 

 Elephas primi genius in illustration. This may well cause suspicion 

 of the numerous speculations on the climate and conditions of the 

 coal-measure period. 



Sucking Disc of the Remora. In " Comptes Rendus" (March 

 18, 18G7) M. Baudelot confirms the opinion of philosophical anat- 

 omists that this disc is the equivalent of a dorsal fin. He shows 

 that each lamina of the disc on the head is supported by a ray 

 sustained by an interspinous bone, and that the movements are 

 effected by small muscles, corresponding to the elevators and de- 

 pressors of fin-raj's. When the laminae of the disc are raised the 

 space between them is increased; the air consequently is rarefied, 

 and, as all communication is cut off from the external air by the 

 raised edges of the disc, the animal thereby attaches itself by a 

 strong power of suction. 



Eggs of Cbrixa Mercenaries The eggs of this kind of bot-fly 

 are deposited on reeds in fresh-water lakes of Mexico ; they are 

 ground by the natives and used as food. They are chemically 

 composed, according to Dr. Phipson, of chitine, which he consid- 

 ers a glucoside, and a little phosphate and carbonate of lime. The 

 eggs are supposed to contribute to the formation of a new oolitic 

 limestone at the bottom of the lakes. 



Period of Incubation of Sharks. According to M. Coste, in the 

 Squalus catulus, Linn., there are laid 18 eggs in the course of the 

 month of April, on the coast of France ; these are hatched early 

 in December, incubation being a period of 9 months. 



Insect Fabricators of Iron. It is well known that some insects 

 are skilful spinners, but it was not known that some of them fab- 

 ricated iron ; A Swedish naturalist, M. du Sjogreen, has pub- 

 lished a curious memoir on this subject. The insects in question 

 are almost microscopic ; they live beneath certain trees, especially 



