304 RECOKD OF CUKKENT RESEARCHES RELATING TO 



of the daugliter-nuclei, do not occupy mucli more than two hours. 

 The granules in the lines first coalesce with one another, although the 

 moniliform contour of the lines is still preserved ; but they gradually 

 become more and more obliterated. The object next becomes again 

 sharper and clearer, and a larger or smaller number of threads pene- 

 trate the nucleus longitudinally, which again arrange themselves in 

 S-like curvatures. These threads next become thicker and smaller in 

 number, and exhibit a variety of patterns ; but these changes proceed 

 slowly, and are difficult to follow. At this stage the nucleus usually 

 appears as if constricted in the middle. 



The threads next begin to straighten themselves, this process 

 advancing from the equatorial regions to the poles, where they some- 

 what approximate ; and thus arises the typical form of the nucleus 

 described by Strasburger as the " kerntonne " or " barrel," * It 

 consists of a relatively small number of comparatively thick threads, 

 or rather rods, which can be followed more or less continuously from 

 one pole of the barrel to the other, both poles being characterized by 

 an accumulation of colourless protoplasm. 



Then follows the rupture of the barrel in its equator, first at the 

 periphery, then in the interior. The rods are simply constricted in 

 the middle, the outermost separating from one another somewhat in 

 the form of a fan. From this time until the formation of the mem- 

 brane of cellulose only about fifteen minutes elapses. 



The two halves of the barrel separate from one another, but all the 

 rods are not ruptured at precisely the same time, so that the sej)aration 

 is not at first very sharp. Between the separated halves of the rods 

 there remains a hyaline substance which, when fresh, is perfectly 

 homogeneous, and remains so with 1 per cent, osmic acid ; but treated 

 with absolute alcohol or 1 per cent, chromic acid the most beautiful 

 longitudinal striation is revealed. There can scarcely be any doubt 

 that this substance was previously present between the rods, for the 

 rods can be seen evidently to withdraw themselves from it. The 

 author is induced to recur to his original view that in the division of 

 a nucleus the rods owe their origin to this substance, which has been 

 taken up into the nucleus, while, on the other hand, in free cell- 

 formation they must, at least mostly, be differentiated from the proto- 

 plasm which surrounds the nucleus. 



As soon as the colourless substance becomes visible between the 

 halves of the barrel, the cell-plate becomes apparent in its equator, 

 composed of a simple row of dark granules, the origin of which is 

 difficult to trace. They soon coalesce into a continuous homogeneous 

 pellicle, which is recognized as the new cellulose-wall. The granular 

 protoplasm collected in the equator of the cell-threads is pressed 

 aside, and the hyaline substance now lies distinctly in the form of a 

 convex lens between the two nascent sister-nuclei, divided by the 

 cellulose-wall clearly distinguishable as a black line. The striation of 

 the hyaline substance is revealed by application of alcohol or 1 per 

 cent, chromic acid. 



These observations seem greatly to increase the importance to be 

 * See this Journal, ii, (1879) p. 910. 



