Dictyoldnesis in Germ Cells. 



241 



In this present paper, we have shown that, in animal germ cells, the 

 Oolgi apparatus may during interkinesis be spread throughout the cell 

 cytoplasm, as in Stenobothrus, or it may be excentric and juxta-nuelear, as 

 with most of the forms herein described. In a previous communication, one 

 of us showed that, in the case of Limax agrestis, the number of dictyosomes 

 or Golgi (nebenkern) rods in the spermatocyte is almost always eight, and, 

 after the two maturation divisions, each of the four spermatids has two rods. 



The size of the rod in the spermatid is the same as that in the 

 spermatocyte, and this, with the evidence brought forward in this paper, 

 shows that each rod passes through the maturation divisions undivided. It 

 had previously been shown that the number and size of the dictyosomes or 

 Golgi rods in such a mollusc as Helix aspersa may vary greatly.* 



Multiplication of the number of the Golgi rods may take place during the 

 interkinesis stages, as was demonstrated clearly in the case of the Limnsea 

 egg,! but no actual division of individual rods seems to occur at cytokinesis, 

 but only a sorting out of whole rods. This is well shown in Plate 18, 

 figs. 19 and 20 of this paper, and was first worked out by J. A. Murray.| 



When we come to the case of some of the mammals, it will be noted that, 

 even though the molluscan dictyokinesis may be haphazard and unequal, 

 that of the mammal is even more irregular. That there is a true 

 dictyokinesis or distribution of Golgi elements during mammalian cyto- 

 kinesis cannot be doubted, but there are several relative points which 

 should be brought to notice. In the first place, the Golgi apparatus of such 

 forms as Mus and Cavia often appears to be a mere cortical layer plastered 

 upon the surface of the centrosphere, separate dictyosomes or rods of any 

 kind being apparently absent. In other cases there are distinct dictyosomes, 

 but these are rarely so well marked as in molluscan germ cells. Dictyo- 

 kinesis in the mammalian germ cells studied by us is never so much a 

 sorting out of distinct rods as in molluscs, as an irregular breaking up of 

 possibly only that part of the archoplasm or centrosphere in close proximity 

 to the more cortically disposed Golgi substance. It is only right to point 

 out, however, that we have found some very clear metaphases where the 

 Golgi elements were composed of discrete dictyosomes, as in Plate 77, fig. 3. 



But we come to another point ; perusal of such work as that of 

 Lenhoss^k§ on the rat will show that such observers figure maturation 

 metaphases with a single free unbroken centrosphere at one pole of the 



* See ' Quart. Jour. Micr. Science,' vol. 62 (1917), Plate 32, fig. 25, and Plate 33, fig. 32. 

 t ' Quart. Jour. Micr. Science,' 1919. 

 I ' Zool. Jahrb.,' vol. 11. 



§ Quoted and figured by Doncaster in his ' Cytology.' 



