Some Remarks on the Cytology of normal and Colchicine-treated Hemp-plants. (Cannabis sativa L.)

Several investigations have pointed out that in the roots of Cannabis sativa the plerome consists for the greater part of diploid cells, while the periblem is tetraploid in the majority of cases. Something like this is further only known for Spinacia and Mercurialis. The origin of these tetraploid cells may be understood in this way that the chromosomes in the periblem divide, but the halves do not separate, in other words, they do not pass the metaphase stage. Hence nuclei are formed, having now double the number of chromosomes. In accordance herewith Langlet found nuclei with chromosomes forming exquisite pairs in the metaphase, which proves that they have just been produced by splitting. Further away from the apex the chromosomes are no longer arranged in this manner (i). Breslawetz only is of another opinion (2). The tetraploid nuclei should proceed from a fusion of two resting nuclei. From this event, which would be unparelleled in cytology, he gives several figures. We also found similar figures in hemp-roots (Fig. 1). The explanation, however, is quite another one. Two nucleoli are clearly seen, each surrounded by a lucid zone. It is generally known that this figure is due to a fault of fixation, in other words is something artificial. The nucleolus possibly pushes the contracting nuclear substance to the periphery by its Brownian movement. Therefore, we are not allowed to identify such a zone with a nucleus, as Breslawetz did. When two nucleoli are present, the zones may border upon each other. It would be wrong to conclude that we have to do with a fusion.