VOLUME XXXVI NUMBER 2 
IDOLANICAL “GAVETIC 
AUGUST, 1903 
STUDIES IN SPINDLE FORMATION. 
ANSTRUTHER A. LAWSON. 
(WITH PLATES XV AND XVI) 
HISTORICAL. 
THE evidence produced from the researches of the last few 
years" proves quite conclusively that a centrosome as a spindle- 
forming organ does not exist in the higher plants. Too few 
forms, however, have been worked out in sufficient detail to 
allow of any definite conclusions as to whether or not these 
plants have any common uniform method of spindle formation. 
Of the types that have been thoroughly examined, the following 
have been recorded: 
In 1897 Osterhout investigated the spindle in the spore mother- 
cells of Equisetum. The first indication of a spindle in these 
cells is the formation of a felted zone of kinoplasmic fibers sur- 
rounding the nucleus. These fibers grow out from the nuclear 
membrane and assume a radial position. By the fusion of their 
free ends these fibers form a series of cones, and upon the break- 
ing down of the nuclear membrane the cones unite at their apices 
in two groups to form the bipolar spindle. 
In 1898 the writer investigated the development of the spindle 
in the pollen mother-cells of Cobaea. Here it was found that, 
as division approaches, a dense granular cytoplasmic substance 
* Belajeff (1894), Byxbee (1900), Davis (1899, 1901), Debski (1897), Farmer (1893, 
1895), Guignard (1898), Juel (1897), Lawson (1898, 1900), Mottier (1897 a, 4,) 
Némec (1898, 1899), Osterhout (1897, 1902), Smith (1900), Strasburger (1896, 1897, 
1900), Webber (1897), Weigand (1899), Williams (1899). 
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