A comparison of Paulmier’s fig. 42 with my fig. 4 suggests the thought that they are the same stage, and his fibers are remains of the spindle. His fig. 43, of course, agrees with my fig. 25; and fig. 43 may correspond to figs. 26 or 14, only that his stain is weaker. Meves’s investigations are the most extensive of the recent ones on the nebenkern. He has used _Paludina_ and _Pygæra_ as his objects. The consideration of the mitochondrion in the spermatocytes I shall pass over, as it is not within the bounds of this paper; yet I hope to study the earlier generations of my material, and shall then compare the results. In Meves’s description of _Paludina_, I find but one point in which it agrees with _Gryllus_. The head of the young spermatozoon in _Paludina_ has a clear space in the center filled with nuclear fluid, which remains till the head begins to stretch. In _Gryllus_ it is hollow until maturity. In _Paludina_ the nebenkern in one kind of spermatids is formed from threads made up of mitochondria—small, round bodies identical with St. George’s cytomicrosomes and Erlanger’s centrodeutoplasm. These threads change to vesicles, which, reduced to four, closely surround the centrosome as it lengthens into the middle piece. At first they form a four-cleft cylinder, but finally a single sheath. An idiozome and spindle remains are seen in the spermatid. They persist for awhile, and the former changes into the acrosome. In _Pygæra_ Meves finds two kinds of spermatids, distinguished by a small difference in size. The larger forms the typical spermatozoon. The spindle remains form a “Spindelrest körper,” which is soon lost. The ends of the mitochondrion chains form a ring of dark mass surrounding a clear space. The ring is broken by radiating clear spaces. These spaces collect and unite into larger vacuoles, which surround the darker center. Finally there is only a dark ball with a surrounding clear space shut in by a ring. The centrosome with attached axial filament fastens itself to the nucleus; then both begin to grow longer. The axial filament passes over the surface of the ring surrounding the ball—the “mitochondrion körper” or nebenkern. This body elongates a great deal then the darker mass puts forth numerous threads which surround the axial filament. As to _Pygæra_, the peculiarity is the complete agreement of his “mitochondrion körper” and my nebenkern in appearance and behavior for a part of the transformation and their complete disagreement in the other part. The question with me is, “Do the two bodies whose final stages are so similar originate so differently, or has one of us mistaken the origin of the body?”