240 Mr. R. J. Ludford and Dr. J. B. Gatenby. 



The archoplasm is seen just dividing, and carrying with it the semi-lunar 

 Golgi rods. The two parts of the apparatus are carried to opposite ends of 

 the cell by the centrosomes, and the spindle arises between them in the 

 normal manner. 



An early anaphase in the primary spermatocyte of the mollusc Limnaea is 

 shown in fig. 20, which is drawn from a Kopsch preparation. It will be 

 noticed that, while the chromosomes are being drawn apart, the dictyosomes 

 are breaking away from the asters. Later they become more scattered, and 

 then, when the chromosomes have reached the poles of the spindle, the 

 dictyosomes are drawn once again to the ai'choplasin. 



The same process is repeated during the second spermatocyte division, so 

 that, in the spermatid, the Golgi apparatus is in the clumped condition. In 

 the formation of the spermatozoon, it is sloughed off along the tail, and is 

 seemingly absent altogether in the mature spermatozoon. 



Dictyokinesis in Stenohothrus. 



Dictyokinesis, as observed in the spermatocyte of the cricket, Stenohothrus 

 viridulus, differs from that described for the previous animals, in that the 

 Golgi elements break away from the archoplasm at a very early stage in the 

 development of the spermatocyte. In Cajal preparations, the apparatus in 

 the spermatocyte appears first as a number of black granules around the 

 archoplasm. Soon these granules break away and scatter in the cytoplasm, 

 leaving the archoplasm, as is shown in fig. 10. 



The end of a typical first spermatocyte division is shown at fig. 11. It 

 will be seen that the Golgi elements are fairly evenly distributed in the 

 secondary spermatocyte. After the second spermatocyte division, many of 

 the dictyosomes become once more attached to the archoplasm, and they 

 remain thus in the spermatid. 



Discussion. 



It seems to be agreed by most observers that, during mitosis, the 

 chromosomes divide longitudinally, that is, if they are elongated in shape. 

 BoUes Lee,* in a recent paper, has dropped a bombshell into the camp of 

 the chromosome theorists and Mendelians, by suggesting that " there is no 

 longitudinal splitting. The division is a transverse one, brought about by 

 a folding of the chromosomes at their middle, and their ultimate segmentation 

 at the bend there formed." It is not our intention at the present juncture 

 to join in this discussion, but, for the purposes of this paper, it may be said 

 that, whether the division of the chromosomes be transverse or longitudinal, 

 it is at least a very equal one quantitatively. 



* ' Quart. Jour. Micr. Science,' 1921. 



