PSYCHE 
VOL. XXX. JUNE- AUGUST 1923 Nos. 3-4 
OCCURRENCE, LIFE-CYCLE, AND MAINTENANCE, 
UNDER ARTIFICIAL CONDITIONS, 
OF MIASTOR. 
By Reginald G. Hakris 
From the Laboratoire devolution des etres organises, Paris, 
Prof. Caullery, Director. 
The genus Miastor is extremely interesting for several rea- 
sons. It was in this genus that paedogenesis was discovered 
by Nicholas Wagner in 1861. Though at first Wagner mis- 
interpreted the phenomenon which he observed, and though 
his observations were doubted, subsequent investigation has dem- 
onstrated the fact of paedogenesis as well as the occurrence of 
polymorphism in this genus. But investigations upon Miastor 
have been limited, due to some extent at least, to the lack of a 
suitable method of maintaining the larvae of this genus in the lab- 
oratory. Now that a method, which will be discussed later, has 
been found, it seems to the writer desirable to make a short re- 
sume of the occurrence of Miastor, its life cycle, and polymor- 
phism among the larvae of the genus. 
Occurrence of Miastor. 
Miastor larvae were first observed underneath the bark of 
decaying trees. I have found them in France under the bark of 
decaying oak, chestnut, and birch logs, and in edible mush- 
rooms. 
Other observers have found Miastor larvae in many kinds of 
decomposing wood and in fermenting beet pulp. It may be 
safely concluded that their occurrence is fairly widespread in 
decaying logs and that they are sometimes present in other vege- 
