REVIEWS AND BOOK NOTICES. 423 
nature and history of these cryptogamia, their relations to each 
other and to common moulds, and their importance as sources of 
contagion ; while, with much good sense and rare judgment, the 
question of treatment is quietly left to the professional books. 
Dr. White’s general introductory view of the microscopic fungi 
is clear and significant, and forms a convenient ground for the 
comparison of views even by those whose ideas are inconsistent 
with it. The nutritive system, or mycelium, consists of slender 
cells or tubes, branched, intertwined, and furnished with occasional 
transverse partitions. This may increase directly by subdivision 
into cells with similar powers of branching and of self-multipli- 
cation, or by the production at the ends of some of the branches of 
minute spherical or ovoid cells inclosed in capsules called spor- 
angia, or growing in bushes or bead-like chains, when they are 
called conidia or spores. These conidia may be found detached, 
- either single or in rows or compound cells, and are capable of re- 
_ Producing the mycelium. Under certain conditions the substance, 
called plasma, of these various forms may become cloudy and 
divided into infinitely small free cells which multiply by self-divi- 
sion and may exhibit peculiar movements. These cells or points, 
if more or less spherical, are called micrococcus ; if somewhat elon- 
gated and swollen at one end, bacteria; and if joined in minute 
chains, -vibriones. They have been much and loosely discussed, 
=~ ire supposed to be the primitive forms of organic life. In 
Suitable fluids they develop into larger cells, single or united and 
Sometimes elongating like mycelium, known as ferment cells. 
This is the submerged form of fungus life, familiarly observed in 
the yeast plant and other ferments ; and is capable of reversion to 
mcrococeus, or under favorable circumstances may attain to 
mycelial and conidial development: It closely resembles the 
Spores of ringworm, ete. 
: These forms make up the structure of the moulds, and their vary- 
'$ Size, shape, and predominance have been regarded as specific 
a characters ; but recent observations show that such variations may 
ve to the nature of the soil and atmospheric’ conditions, and 
e the recently recognized species are often varieties of well 
ah he individuals, prevented from their usual development by 
` "cumstances of position. This tendency to variation has been 
ned pleomorphism. 
. These low forms of vegetation occasion the processes of fermen- 
