Rudolph Beer 215 



second meiotic division in the usual manner. Spindles, varying in size 

 with the number of chromosomes, are developed in association with each 

 nucleus, and the course of mitosis proceeds in ([uite a normal manner. 

 No irregularities in the distribution of the daughter-chn^nosomes arc to 

 be seen in this division. 



PI. XXII, fig. 17 gives a representation of the second meiotic division. 

 Single chromosomes each associated with a small spindle can be seen in 

 fig. 14. In PI. XXIII, fig. 16 we have a case which probably represents 

 the second division of one of the large, irregular nuclei referred to 

 above and represented in fig. 12. 



The nuclear divisions which have been described in the foregoing 

 account are followed by the division of the cells so that each nucleus 

 becomes associated with a distinct cell. 



PI. XXIII, fig. 19 represents a mother-cell which has divided up in 

 this manner to form the initials of a number of pollen grains. 



In fig. 18 ten pollen grains will be seen to have developed fi'om 

 a single mother-cell. 



It is readily apparent that the size of the pollen cell is dependent 

 upon the size of the nucleus with which it is associated and this, in turn, 

 depends upon the number of chromosomes which enter into its com- 

 position. The details of this relationship will not, however, be dealt with 

 in the present paper. 



From what has been said above it will be seen that no evidence was 

 found of the existence of secondary divisions of the cells such as Wille 

 described, nor do the present observations give any support to this 

 author's suggestion that a fusion (or non-separation) of jjrimitive mother- 

 cells might occur in those cases in which the supernumerstry microspores 

 were very numerous. 



In addition to the variety "Alice Hoifman " the meiotic divisions 

 of Fucltsia globosa and Fuchsia corallina were studied in detail. In both 

 these plants more than the normal numbei* of four microspores are 

 produced fi'om each pollen mother-cell. It was found that the distribution 

 of the chromosomes during the first meiotic division is quite similar to 

 that taking place in " Alice Hoff'man " and that single chromosomes, or 

 small groups of them, become separated from the rest, and usually give 

 rise to small nuclei. Here also some of the isolated chromosomes may 

 fail to organise imclei, but undergo degeneration instead. It will be un- 

 necessary to describe the details of meiosis in these two forms, but it 

 will be sufficient to call attention to PI. XXIII, figs. 20 — 24 which 

 represent the principal facts of interest. 



