﻿BOTAMCAL GAZETTE 



been found in the literature showing that the double nature of the 

 spirem of the heterotypic mitosis is due to the splitting or 

 vacuolization of somatic chromosomes in the early prophase. 

 In a paper on Galtonia by Miss Digby (7), the split for the 

 division at metaphase of the somatic mitosis is shown to arise 

 by the vacuolization in early prophase, thereby forming the 

 split or the double thread. A similar condition is found in Vicia 

 Faba by Sharp (28), and by Fraser and Snell (12). As the 

 result of the conditions found, Miss Digby says: "By taking a 

 broad and comparative view of this heterotypic prophase in relation 

 to the somatic prophase, one is forced to admit that the parallelism 

 of the one is homologous with that of the other " ; although in her 

 conclusion she states that "the parallel portions in both represent 

 longitudinal halves of somatic chromosomes, and are probably 

 sister halves of the same chromosome, which are now severally 

 coming together and condensing to form the somatic or univalent 

 chromosome." The series of drawings are incomplete at this 

 critical period, and any conclusion would have to be based upon 

 her drawings 39a and b, and 40, none of which is later than the 

 writer's figs. 3 and 5. Furthermore, steps illustrating the origin 

 of these figures from figs. 30 and 31 have not been shown, and the 

 gradual transition from the "beaded" resting nucleus (Digby 7, 

 figs- 33> 3 6 > 37) to tne double condition of the spirem after synapsis 

 appears to be more of a theory or an inference than a statement 

 of observed facts. 



In the early prophases of the heterotypic mitosis of Vicia Faba, 

 Miss Fraser (ii) finds conditions corresponding to those observed 

 in Allium tricoccum. In this paper she describes diamond-shaped 

 meshes that are due to the splitting of the somatic chromosomes in 

 the early prophases; then later, that is, in synapsis, the cross- 

 connections between the meshes breaking down, thus forming the 

 spirem; and finally, in early anaphase, each chromosome splitting 

 preparatory to homotypic mitosis, the origin of the split having 

 been seen in the diamond meshes. The idea is very similar to that 

 described by the author, but as in the paper by Miss Digby (7), 

 Miss Fraser fails to have a series sufficiently close to demonstrate 

 the origin of the split and the formation of the spirem from these 



