70 
Tli. II. Montgomery, jr. 
proves the morphological separateuess of cliromosomes at that time. 
But iu the succeediug prophases of the first cleavage mitosis two 
separable chromosomes reappear iu eacli prouucleus. Figiires 48—52 
iliustrate such prophases before the dissolution of the nuclear mem- 
braue; all except Fig. 51 represent both prouuclei. They show that 
the chromosomes of a particular prouucleus are uuequal iu leugth, 
coustautly so, aud the louger oiies are marked iu these figures by 
the letter »x«. The dilfereuce iu leugth is really greater thau the 
drawings iudicate, because the plane of the paper cauuot adequately 
reproduce the depths and heights of the twistiugs helow and above 
that level. Sometimes this leugth ditference is very marked as in 
Fig. 51, aud not iu a siugle case have I fouud the two elemeuts of 
a prouucleus of even approximately equal leugth. Figures 43 — 47, 
Fl. 7, show later prophases wdieu the nuclear membraues have dis- 
appeared aud the chromosomes become more coudeused. The latter 
are still iu tw’o groups, oue materual aud oue paterual, aud iu each 
group (except the right haud oue of Fig. 46 that wuxs not wholly in 
the plane of the sectiou) a larger oue (marked »x«) is clearly distiu- 
guishable from a smaller. To these may he added Fig. 27 of my 
former ])aper (1904), and Boveki’s (1888) Figs. 23 and 38. 
It follows that in all the cases examiued, where all the chro- 
mosomes could be clearly seeu for thcir full leugths, there proceeds 
from each ])rouucleus coustautly oue louger aud oue shorter chro- 
mosome. 
Oue curious pheuomeuou of this stage may be noted. In some 
cases (Figs. 49, 51 the chromosomes of the prouuclei have much 
the ai)})earauce of those uudergoiug the diraiuutiou process of the 
cleavage: the euds aloue are solid aud thick while the intermediate 
portious are beaded, composed of successive discs aud masses. This 
is au uuusual condition, possibly ])athologic; it is of iuterest iu iu- 
dicatiug that the begiuniugs of the diminutiou process may occasio- 
ually be fouud so early as the stage of the i)rouuclei. 
4. The Chromosomes of the First and Second Cleavages. 
Figures 1 — 35, PI. 6, show pole views of ecpiatorial plates of 
the first cleavage. Where they could be determiued the two larger 
chromosomes are marked »x«. It will be seeu that two louger chro- 
mosomes can with ease he distiuguished from two smaller in all 
cases but three, uamely, Figs. 25, 30, 34, though eveu in these ex- 
ceptioual cases the chromosomes are of ditfereut leugths. It Stands 
