THE SEED PRODUCTION OF PINUS SYLVESTRIS. 31 



would be to omit a most important result of the study. 

 I have been fortunate in securing a very large number of 

 mitoses in which the chromosomes can be studied and 

 counted with ease. In the cells of the various tissues they 

 are normally more or less U or Y shaped. Occasionally 

 they are found as short thick rods ; these are probably 

 abnormal, for they are found in abnormally large, or in 

 ill-developed cells ; these rod-like chromosomes are 

 sometimes invested with a fluffy covering, having the 

 appearance of a stick covered with pencillium or such-like 

 fungus. I have one example of the rod-like chromosomes 

 of peculiar interest, as in one section ten of the chromo- 

 somes are approximately in one plane, the adjoining 

 section contains the other two. This is an abnormally 

 large jacket cell (fig. 16). These jacket cells possess many 

 peculiarities, and present many problems for solution. 



There are 24 chromosomes in the cells of the sporo- 

 phyte, and 12 in those of the gametophyte. They have 

 been counted in a very large number of examples in both 

 generations, and in no instance where a complete count 

 was possible was any other number found. These 

 numbers were found in abnormal forms also. In 

 the sporophyte they have been counted in the leaves, 

 stem, and the various tissues of the cone, in the first and 

 following divisions of the fertilised egg, and in the 

 developing embryo. In the gametophyte they have been 

 counted in the micro- and macro-spores, the jacket cells, 

 the cells of the endosperm, and in the central cell' when 

 cutting off the ventral canal cell. 



And thus I bring the rough summary of a six years' 

 work to a close. I have endeavoured to compress into as 

 brief a space as possible the outlines of a vast and 

 fascinating subject. I fear I have attempted too much, 

 but hope that by the aid of the lantern slides you have 

 been able to follow me. 



