BIOLOGY. 307 



straw, and hay seeds, and some very thin and transparent portions 

 of weather-worn ve.ijetation ; there were also some hairs of leaves 

 of plants, and fibres like fihinients of cotton, and some fragments 

 of wool. 



These floating particles in the air will difl'er in character accord- 

 ing to the season of the year, the direction of the wind, and local- 

 ity, and are much less in quantity after rain. In the above exper- 

 iments, it is estimated that 37^ millions of those spores, exclusive 

 of other substances, were collected from 2,495 litres of air, — a 

 quantity which would be respired in about 10 hours by a man of 

 ordinary size, when actively employed. There was a marked ab- 

 sence of particles of carbon among the collected matter. — Chemn 

 teal News, April, 1868. 



THE POISON GENERATED IN PUTREFACTION. 



Drs. Bergmann and Schmiedeberg have communicated to the 

 "Centralblatf (German) an account of the isolation of a crystal- 

 line substance, which they believe is the proper poison generated 

 in putrefactive fermentation. This poison, the terror of the dis- 

 secting-room, has hitherto been known only by its effects. The 

 London •' Lancet" gives the following details of the preparation 

 of this substance which these chemists have succeeded in isolating. 

 It is obtained by ditFusion through parchment paper, precipitation 

 with corrosive sublimate from an alkaline solution, removal of the 

 mercury by silver, of silver by sulphuretted hydrogen, evapora- 

 tion, and purification of the residue. Large, well-defined, acicu- 

 lar needles are thus obtained, which are deliquescent in the air, 

 and, exposed to heat, melt and carbonize. They possess a power- 

 fully poisonous action. A solution containing scarcely more than 

 one-hundredth of a gramme was injected into the veins of two 

 dogs. Vomiting was immediately induced, and after a short 

 time diarrhoea, which in the course of an hour became bloody. 

 After nine hours the animals were killed, and, on examination, 

 their stomachs and large intestines were found ecchymosed, and 

 the small intestines congested. — Scientific American. 



SIAMESE TWINS. 



There never has been a question among medical men, either in 

 this country or in Europe, in regard to the feasibility of the sep- 

 aration of these two individuals ; that they are two beings having 

 distinct segregated and perfect organizations, one from the other, 

 as any other two individuals; that there is no physical, moral, or 

 mental unity between them, the only connection being a short 

 cartilaginous and integumental band common to the two, the sev- 

 erance of which would, in all probability, be entirely harmless; 

 that no " sensations, nervous impressions, physical, morbid, men- 

 tal, or nervo-mental condition " ever exhibited a " physical unity 

 in their dual corporeal existence ; " that they have no unity of 



