BIOLOGY. 279 



production of cholera, cannot he disputed ; and it possesses this 

 property, when largely diluted in water. If water thus contamin- 

 ated be supplied to a family simply, we have sporadic cholera ; if 

 to a large community, the disease becomes an epidemic. 



Cholerine. Dr. Frankland has been investigating some of the 

 physical properties of cholera matter, cholerine. He shows that it 

 passes through filtering paper, and water containing one five- 

 hundredth of the matter is not entirely purified by transmission 

 through animal charcoal. 



Selachians. At the 1867 meeting of the National Academy of 

 Sciences, at Hartford, Conn., Prof. Agassiz claimed that the order 

 of selachians (sharks and rays) constitutes a type of a special 

 mode of vertebral structure. They have a tail of certain dimen- 

 sions as compared to the body, and they are the only fishes in 

 which the head, chest, abdominal, and caudal regions are to be 

 found. They are also remarkable for the structure of their brains. 

 It may also be added that, like some reptiles, they are viviparous 

 in their mode of reproduction. 



Moulting in Fishes. It is well known to ichthyologists that the 

 skin in many fishes, especialty the Cyprinidaz, becomes the seat of 

 a more or less confluent eruption of small, hard, whitish tubercles, 

 during the period of reproduction. These tubercles have led to 

 the establishment of species, and even of genera. These tuber- 

 cles are temporary ; they vary in size and prominence, and are 

 most conspicuous on the upper surface and sides of the head, ad- 

 herent to the subjacent skin. They consist of superposed layers 

 of epithelial cells, flattened and united, and consequently belong 

 to the epidermic structures. After the reproductive season these 

 tubercles fall with the epidermis to which they are attached, con- 

 stituting a veritable moult, as in batrachians and reptiles. 



Infusoria in Whooping Cough. According to M. Poulet, in the 

 vapors resulting from the respiration in this disease, microscopic 

 examination detects great numbers of small infusoria. The most 

 abundant, as well as the smallest, he refers to the species described 

 as Monas (Bacterium) termo ; others, less numerous, slightly spin- 

 dle-shaped, two or three-hundredths of a millimetre long, and 

 about one-fifth as wide, belong to Monas (Bodo) punctum or Bac- 

 terium bacillus of the micrographers. Thus, whooping cough, in 

 the alterations of the expired air, ranges itself in the class of in- 

 fectious diseases, with small pox, scarlet fever, and typhoid fever. 



Egg of Epiornis Maximus. This bird, attaining a height of 

 about 4 metres, had an egg whose volume equalled that of six 

 eggs of the ostrich. In a specimen recently received at Toulouse 

 from Madagascar, the dimensions were as follows : thickness of 

 shell, m. 0035 ; large diameter, m. 310; small diameter, m. 255 ; 

 greater circumference, m. 87 ; lesser, m. 76 ; capacity, 8 1-10 

 litres ; color yellowish white, with a few streaks of dendritic 

 form and brownish-red color. 



Form of the Trunk of Trees. According to M. Musset, " Comptes 

 Rendus," Sept. 2 and 16, 1867, all trees have an elliptical trunk, 

 the greater axis directed sensibly from east to west. As the cen- 

 trifugal force developed by the rotation of the earth, according to 



