342 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 30 Ser. 



occupies this position becomes, as a rule, more prominent 

 than those surrounding it. These two cones remain the 

 most prominent ones. More or less parallel to the axis of 

 these cones, and consequently more or less parallel to the 

 longer axis of the nucleus, run the linin threads. The 

 multipolar diarchal nature of the spindle is even more 

 prominent in the second division. 



Thanks to the numerous investigations of recent years, 

 we are now able to compare a number of modes of spindle 

 formation. Strasburger (1900, p. 118) distinguishes three 

 types of spindle formation; the multipolar polyarchal, the 

 multipolar diarchal, and, opposed to these, the bipolar 

 diarchal. 



Multipolar polyarchal spindles are characteristic of the 

 first division of pollen-mother-cells (Liliitm^ Passiflora, 

 Lavatera, Cohma, Gladiolus) and of spore- and embryosac- 

 mother-cells (Osterhout, 1897; Strasburger, 1900, p. 121). 

 In Cassia tojnentosa we have a multipolar diarchal spindle 

 Anlage in the first division, which thus forms a connecting 

 link between the multipolar polyarchal spindle Anlage of 

 reproductive cells and the multipolar diarchal spindle de- 

 scribed for vegetative cells, i. e., the root-tips of Vicia 

 (Strasburger, 1900, p. 116), of Allium (Nemec, 1899^), 

 and of ferns (Hof, 1898, p. 169). In NymfhcBa alba 

 (Strasburger, 1900, p. 122) the spindle Anlage of the 

 mother nucleus does not differ essentially from that in the 

 daughter nuclei described by Strasburger for Iris squalens, 

 where it is multipolar diarchal. 



It seems therefore that there exists no sharply marked 

 difference between spindle formation in reproductive and 

 in vegetative cells, and that the two processes are closely 

 related. 



As suggested by Strasburger (1900, p. 122), the various 

 modes of spindle formation would readily lead one to 

 suppose them influenced by polarity: " Eine Pollen- 

 und Sporenmutterzelle konnte auch in ihren Protoplasten 

 multipolar sein und so die polyarche Anlage der Kern- 

 spindel bedingen. Auch liesse sich denken, das die 



