PUTREFACTION IN BLOOD. 63 



Even while writing this, I am aware of many opposing 

 facts and opinions. Whilst the surface-water of the ocean 

 contains a considerable amount of organic matter, I have 

 not found more in the atmosphere, on a calm day, over the 

 sea than over mountains, but a large amount during a 

 slight wind. In working on putrid matters, the vapours 

 pass through porcelain which is unglazed, though very 

 compact, under circumstances which seem to forbid any- 

 thing but the most perfectly gaseous matter to rise. I 

 am aware, too, that I must not be led away by analo- 

 gies to suppose that bodies in the state of vapour cannot 

 undergo putrefaction ; and I will even go further, and say 

 that the afiirmative hypothesis would explain a larger 

 number of phenomena as they appear to us at present. 

 We must beware of fancies in this dark region. 



P.S. I may mention that even 130° Fahr., nearly 

 55° Cent., does not prevent putrefaction, which probably 

 ceases at 140° Fahr., 60° Cent., the point of the coagula- 

 tion of albumen. 



V. On certain Scales of some Diurnal Lepidoptera. 

 By John Watson, Esq. 



Bead before the Microscopical Section, November 18th, 1861. 



The scales of lepidopterous insects have long been subjects 

 of microscopical examination; but it may be questioned 

 whether sufficient notice has hitherto been taken of their 

 peculiarities, with a view to the determination of the genera, 

 species, and affinities of the insects, or of their systematic 

 functions. 



The ordinary scales are more or less oval, showing from 

 2 to 5 or more dentations at the broader end, and having 

 a short, stiff, pointed peduncle at the other extremity, by 



