Notes on Recent Literature. 
23O 
division of the pollen. The chromosomes, like the chromatin 
granules, showed great variety of size, and, moreover, both granules 
and chromosomes were sometimes clearly seen to be arranged in 
pairs, or in groups of larger number. As Strasburger showed 
earlier in Galtonia and Funkia the reduction in number in these 
cases is to be considered as a result of the association of somatic 
chromosomes. It is clear that such association will have no general 
physiological or genetic significance so long as these elements 
appear in their full number at the reduction-division. The actual 
chromosome number is obviously unimportant, for two closely 
allied species may have widely different numbers of chromosomes, 
although the number of pangens (or determinants) carried would 
seem to be about the same. In the modern view the chromosomes 
are only segments of a thread bearing the pangens in rows. 1 
These observations of Strasburger are of particular interest at 
a time when the question of the behaviour of the somatic chromo¬ 
somes is coming more and more into prominence (cf. the previous 
number of this journal, p. 149). In relation to the behaviour of the 
embryo-sac-mother-cell of Wikstrcemia indica, Strasburger finds 
that although the first division spindle suggests a meiotic phase, 
yet there is no synaptic contraction and the number of chromosomes 
is comparable to that of many somatic nuclei, for it is variable and 
never reaches the full number. There is clearly no reduction. The 
second division is absent so that no tetrad, but only two sister-cells, 
are produced, the lower one of which becomes the embryo-sac 
bearing the diploid egg. 
A comparison with other normal members of the Thymeleaceas, 
namely, Daphne Mezereum, D. alpina and Gnidia carinata showed 
that while all these species have 9 chromosomes in the haploid 
state, Wikstrcemia indica has 26. In its comparatively large number 
of chromosomes this species resembles the apogamous members of 
the Rosacete and Compositas. The apogamous Antennaria alpina, 
for example, has more than twice as many chromosomes as the 
normal A. dioica. As in some other examples, apogamy in this form 
is associated with polymorphism, for W. indica is a collective 
species. An examination cf the various forms placed under this 
name in the Berlin herbarium showed that more than two-thirds 
have well developed pollen. A close study of the species would no 
doubt show all stages from normal, sexual ones to apogamous. 
Strasburger then turns to a short discussion of the reduction- 
division. He points out that a generally accepted view as to the 
nature of the prophase of this division is still wanting ; in fact, of 
] When one considers that in a given species the number of 
chromosomes, though hereditarily fixed, appears to be purely 
arbitrary, it is astonishing that the variation is usually within 
such small limits. It may be suggested that individual 
variations in number (apart from the temporary linkages 
described above) would probably tend to prevent cross¬ 
pollination by rendering difficult the proper pairing at meiosis, 
owing to the inequality in number of chromosomes derived 
from the two parents. It would be interesting to compare the 
variation in chromosome-number of plants normally self- 
pollinated or apogamous with those normally cross-pollinated. 
It has already been pointed out by Strasburger that apo¬ 
gamous forms usually have a relatively large number of 
chromosomes. 
