272 J. B. S. MOORE. 



become so much altered in their refractive characters that one 

 is reminded of Flemming^s words when describing a similar 

 change witnessed in the dividing cells of the salamander : 



"Bekommt man unwillkiirlich den Eindruck, als sei die 

 Zelle wahrend ihrer Theilung durch und durch rait einer be- 

 sonderen Substanz durchtrankt oder — um mich vorsichtiger 

 auszudrucken — als besitze sie durch und durch eine besondere 

 physikalische oder chemische Beschaffenheit." 



This change appears in the spermatocytes of Branchipus to 

 be the direct result of the collecting of the primarily diflfuse 

 staining material of the resting nucleus into ten chromosomes, 

 and of that existing in the kytoplasm without into distinct 

 chromatic bodies (dictyosomes). Both these changes are appa- 

 rently due to a progressive fusion or running together of the 

 clear globules which, begun within the nucleus, formed the 

 chromosomes on its surface, and extending, swept the diffuse 

 staining material of the cell body together into some twenty 

 dictyosomes on its circumference. In this brief and necessarily 

 crude manner I hope to have made the main drift of the investi- 

 gation up to this point clear. I have dealt with the develop- 

 ment of the chromosomes in Branchipus, and shown reason to 

 believe that it is in a measure dependent on a fusion of the 

 globules which give rise to the reticulate appearance. The 

 progress of such a fusion would produce the one-sided figure 

 described by Hermann in the spermatocytes of the salamander, 

 and tend ultimately to form a limited number of chromosomes 

 all on the nuclear periphery; and we have seen that during 

 these changes there exist in the resting spermatocytes those 

 dark points (pseudosomes) whose appearance corresponds in 

 everything but number with the centrosomes of previous 

 authors. 



We have seen also that the fusion producing such wide 

 changes in the nucleus spreads beyond it, leaving the chromo- 

 somes suspended to the pseudosomes. These pseudosomes 

 retreat with the remnant of the original network as it vanishes 

 towards the periphery, and in connection with this motion an 

 axis tends to be set up round which the spindle figure gathers, 



