168 BOTANICAL GAZETTE [AUGUST 
agent and Haidenhain’s iron alum haematoxylin, or Flemming’s triple stain, 
the young cells, especially of the dermatogen and plerome, show an intricate 
network of canals, and older cells show a gradual transition from the network, 
which is a single structure, to the familiar appearance obtained by current 
methods. This method promises to solve the problem of the origin of the 
vacuole, and at the same time it is excellent for nuclear structures.—CHARLES 
CHAMBERLAIN. 
Mitochondria.—The small bodies variously known as mitochondria, 
chondriosomes, chondriokonten, and chromidial substance, have been known to 
zoologists for some time, but it is only recently that they have attracted any 
serious attention among botanists. A short paper by Lewrrsxr* describes * 
the mitochondria in young cells of Pisum sativum and Asparagus officinale. 
In the root tip the mitochondria become transformed into leucoplasts, and 
in the stem tip into chloroplasts. The mitochondria divide and are believed 
to be an essential part of the cytoplasm. No mitochondria were found inside 
the nucleus, and the author does not believe that there is any passage of 
mitochondria between nucleus and cytoplasm. Division of mitochondria is 
figured and described.—CuarLes J. CHAMBERLAIN. 
Origin of the plastid.—For nearly twenty years the theory that the plastid 
is a permanent organ of the cell, arising only by the division of a preexisting 
plastid, has been generally accepted, doubtless on account of the thorough 
investigations of ScHIMPER and of MEYER. When Lewirskt’s paper appeared, 
laimi 
plastid arises only by the division of a pre-existing plastid. Their evidence 
seems more voluminous than convincing. It is to be hoped that this incipient 
controversy will settle the status of the plastid —CHartres J. CHAMBERLAIN. 
24 LEWITSKI, G., Ueber die oa in pflanzlichen Zellen. Ber. Deutsch. 
Bot. Gesell. 28:538-546. pl. 17 oO. 
25 MEYER, ARTHUR, eee zu G. Lewitskt: Ueber oa Chondriosomen in 
pflanzlicher Zallen, Ber. Deutsch. Bot. Gesell. 29:158-160. 1 
