blackman: the spermatogenesis of scolopendra. 117 



panied by figures, it is difficult to compare the phenomena observed by 

 them with those occurring in Scolopendra. Yet their recognition of tho 

 centrosome within the nucleus seems significant. It would appear likely 

 that a further study of Geophilus might reveal a condition more nearly 

 approaching that in my material. From their description, and in the 

 ahsence of figures, it seems possible that the double " centrioles" described 

 may correspond to the centrosomes within the nucleus of the mature 

 spermatozoa of Scolopendra. 



It is much more difficult to correlate the observations of Tonniges 

 upon Lithobius with the processes which I have observed in Scolopendra. 

 After the completion of the second spermatocyte division the centrosome 

 lies upon the nucleus. Soon, however, it " verlasst seine Stellung am 

 Kern and l'iickt an die Peripherie der Zelle. Dicht an diese ange- 

 driickt findet es sich als ein kleiner, sehr dunkel gefiirbter, zweitheiliger 

 Korper, dessen beide Ilalften durch eine hellere Substanzbriicke ver- 

 bunden sind. . . . Sie riicken bald wieder von der Peripherie ab, 

 nehmen aber von ihr einen dlinnen Faden, den Axenfaden mit, der sich 

 zuerst ganz dicht an sie anschmiegte und erst allmalig mit dem Weiter- 

 wandern der Centrosome von ihr abloste." As the centrosome approaches 

 the nucleus, the nuclear membrane is drawn out into a protuberance, 

 whereas later, when it comes to rest upon the nucleus, it lies in a small de- 

 pression. In several of his figures, however, the centrosome seems to lie 

 entirely inside the nuclear membrane. Soon the archoplasm in the region 

 of the centrosomes gives rise to the Faserkorb mentioned above, and 

 botli cell and nucleus continue to elongate. " Innerhalb des Faserkorbs 

 vollzieht sich die weitere Umwandlung der Centrosome, und zwar besteht 

 dieselbe zunachst darin, dass sich der distale Theil ablost und in das 

 C\'t<>plasma vorriickt, eine Zeit lang noch durch einen Faden mit dem 

 anderen in Verbindung bleibend ; spater legt er sicli dem Axenfaden 

 an und bildet einen Ring, der ziemlich nahe am proximalen Centrosoma 

 liegt, welches letztere zum Endknopfchen gew 7 orden ist." The section 

 lying between the two centrosomes Tonniges interprets as the middle 

 piece. 



The observation of Tonniges in regard to the centrosomes which is 

 most, at variance with those on Scolopendra is the one concerning the 

 transformation of the distal centrosome into a ring surrounding the axial 

 filament. There are most certainly no appearances in Scolopendra which 

 could lead to such a conclusion, and it may be added that the figures of 

 this process given by Tonniges are not very convincing, for his "rings" 

 have the appearance of mere thickenings of the axial filament caused by 



