CHIROXOMUS PRASIXUS. 1G7 



means he succeeded in showing that the germinal vesicle of the 

 ovarian ova of a rabbit enclosed a network formed of uniserial 

 rows of globules, and not homogeneous filaments. In many- 

 cases these nuclear grains, instead of being globular, are disc-like, 

 resembling rouleaux of blood-globules, and this is especially the 

 case in Chi7'o?iomus^ where the nuclei of the salivary glands, in 

 which the phenomena are most strikingly shown, enclose, firstly, 

 two large nucleoli, sometimes separate, sometimes more or less 

 united (see Fig. i6) ; and secondly, a coiled, cylindrical cord of 

 slightly varying diameter ; sometimes continuous, sometimes in- 

 terrupted, and occasionally doubled ; the extremities of which 

 pierce the nucleoli (see Fig. i6). At a small distance from each 

 extremity there is an abrupt discoid swelling, which may be 

 described as a ring which the cord traverses a little before the 

 extremity pierces the nucleolus. This ring is difficult to see in 

 living cells, but is brought out by re-agents, colouring matter, etc. 

 The structure of the cord presents alternate dark and light bands, 

 the former of which appear to be formed by a solid substance, the 

 latter by a liquid. These bands are the expression of thin discs, 

 which are quite independent of each other, as may be seen when 

 separated by pressure. It will scarcely be questioned, Balbiani 

 says, that the cord is the homologue of the intra-nuculear network 

 of other nuclei, which are generally described as consisting of 

 homogeneous threads continuous with the wall of the nucleus, and 

 branching and anastomosing therein. Are these, however, he asks, 

 the characters of the fresh and living nuclei ? It has been stated 

 that the prolonged use of re-agents beyond the time required for 

 fairly bringing out the phenomenon in question, destroys the 

 utility of their application ; nay, more, knots up the cord and fuses 

 the discs with one another ; and this is what he thinks has 

 happened with many observers who thus have only described 

 homogeneous, intra-nuclear networks, where otherwise they might 

 have described structures similar, more or less, to those so 

 beautifully seen in this insect. He observes, finally, that the nuclei 

 of CJiironomus are truly organisms — ?>., they are provided with 

 special parts fulfilling special functions, and perhaps this inference 

 may extend to both animal and vegetable kingdoms. There is 

 no doubt that there is exhibited in these nuclei a high degree of 



VOL. IV. N 



