1910] CURRENT LITERATURE 67 
division of the ascus nucleus, which differs little in appearance from the normal 
vegetative type of division, is described as brachymeiotic, in which half the hetero- 
type number of chromosomes is present, thus bringing about, as is believed, a 
second reduction in the number of chromosomes. In Ascobolus furfuraceus 
and Humaria granulata they find that the eight chromosomes are paired through- 
out the second and also in the prophases of the third division. In Lachnea 
stercorea, in which the meiotic prophases were studied more in detail, the hetero- 
type number of chromosomes is four, two chromosomes being much longer than 
the other two. The first numerical reduction occurs by an end-to-end union of 
the chromosomes, which are subsequently separated transversely. In the third 
metaphase four chromosomes are present. Two entire chromosomes, one long 
and one short, pass to each daughter nucleus. 
Brachymeiosis is believed to differ markedly from meiosis in several particulars. 
In meiosis it is held that the most essential feature seems to be the union of two 
chromosomes to form so-called gemini, while brachymeiosis may be accom- 
plished without visible union of the chromosomes, as described for Lachnea 
slercorea, and when pairing does occur in this division, as described for Ascobolus 
jurjuraceus and Humaria granulata, the opportunity for interchange of material 
is held to be much less than in meiosis. It is believed, therefore, that it is possible 
to distinguish between sexual and asexual fusions by a study of the subsequent 
reduction divisions. (The reviewer cannot agree with these authors that the dis- 
tinguishing characteristic of meiosis, at least the visible distinction, rests on the 
Close association of the chromosomes. The conspicuous fact is the formation of 
tetrads or so-called four-parted chromosomes. The formation of tetrads does 
hot necessarily imply any very close association of the constituent parts of two- 
parted chromosomes.) 
In the opinion of the authors the parental allelomorphs and also those brought 
together by the nuclear fusion in th ; show varying deg f association, 
and this is brought out by a text figure, in which the forms here studied are com- 
Pared with several other Ascomycetes. In Humaria granulata pairing of the 
chromosomes is present in the pre-meiotic divisions, while this pairing occurs in the 
meiotic prophases in Ascobolus furfuraceus, thus resembling Otidea aurantia and 
Pesiza vesiculosa in this respect. 
The authors also find that an important part is played by vacuoles in spore 
delimitation. They find in Ascobolus a differentiation into dense and vacuolated 
areas, but also that the center and astral rays are essential to spore delimitation. 
After the third division the cytoplasm becomes traversed by an irregular series 
of vacuoles or areas of cleavage, which separates the sporeplasms. It is nel 
that a substance flows out from the center, capable of producing alterations in the 
‘ytoplasm, probably an enzyme. A definite membrane is put about the spore- 
plasm, and a similar one limits the neighboring periplasm, with a clear space 
tween, marking the old lines of cleavage. Although these observations support 
Faut’s views, they also support the view that the astral rays play an important 
Part in spore delimitation.—J. B. OVERTON. 
