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REVIEW OF BIOLOGY. 
The recent studies upon putrefaction show that microbes 
of different species follow each other regularly in the many 
complex phenomena of putrefaction, and that their action is 
every time marked by the formation of gases with various 
odors; these gases, detected by the insects even at long dis¬ 
tances by their powerful and delicate olfaction, tell them of 
the degree to which the putrefaction has arrived, and thus 
allow them to select the one most convenient for the deposit 
of their eggs. Thus is explained the regular succession of 
the insects that Messrs. Megnin and Brouardel have called 
the workers of death, which are, consequently, the true reac¬ 
tives of the various degrees of putrefaction. These insects, in 
fact, continue their work even after the work of the microbes 
is ended ; if there remain some small organic fragments, ten¬ 
don, ligament or skin, which, hard and dry, have resisted 
putrefaction, they are destroyed by these gnawing insects, 
which thus come to complete the work of their predecessors. 
The first corps d'armee which enter a cadaver is formed of 
flies of the Ciirtonevea and Calliphora species; their presence 
is even sometimes detected before death. They prefer fresh 
meat. 
The second is composed of Liicilia and Sarcophaga , with— 
in some cases— Uropada . They are present only when the 
odor of putrefaction is well manifest, from three to six days 
after death. 
The third is constituted by coleopters of the Dermestes 
kind and lepidopters of the Aglossa. They appear three or 
four months after death. 
The fourth consists of some flies, Pioplata and Anthomyia , 
with coleopters. of the Necrobia species. They appear toward 
the eighth month. 
At a later period, when the soft tissues are transformed 
into a blackish pulp, come the flies of the Ophira , Phora and 
Tyreophora species. The cadaver is then about one year old. 
When it is eighteen months or two years old, arrive cole¬ 
opters of the Silpha, Hister and Sopnnus species, with acari of 
Tyroglipheas. 
The seventh army is composed of coleopters and lepidop- 
