Anatomie. — Morphologie, Teratologie, etc. 
3 
ward and bordering on a central, thinwalled parenchyma. An almost 
cjdindric outline is characteristic of the section Eviphilema , with a 
corresponding arrangement of the mestome-bundles, but otherwise 
the structure is almost identical. The chlorenchyma consists of pa- 
lisades vertical to the surface in the sections Bermudiana, and 
Eviphilema , while in Echthronema the cells are shorter, lobed, and 
parallel with epidermis. Some few examples of a similar Variation in 
the structure of the chlorenchyma is mentioned as characteristic of 
Iris cristata, I. verna and I. fulva , Tapeinia, Freesia , Tritonia, and 
Belamcanda. As to the peculiar arrangement of the mestome-bund¬ 
les in the leaf of Sisyrinchium , being located in a plane or in an 
elliptic band, similar Variation exists, also, in various species of Iris. 
Theo Holm. 
Mottier, D. M., The Development of the Heterotypic Chro- 
mosomes in Pollen Mother Cels. (Annals of ßotany. XXI. 
p. 307 — 347 . PI. XXVII and XXVIII. 1907 .) 
The mitotic history from the resting stage of the pollen mother- 
cell nucleus to the complete formation of the heterotypic chromo- 
somes is described for Podophyllum peltatum, Liliam Martagon, and 
L. candidum. Some observations were also made on Tradescantia 
virginica and Galtonia caudicans. The chromatic masses in the presyn- 
aptic nucleus were found to vary much in size and shape, and there 
was no definite relation between the number of these lumps and 
the number of somatic chromosomes. The author concludes that in 
the plants examined there is no evidence to Support the u pro-chro- 
mosome theorv” associated with the names of Rosenberg and 
Overton. He also considers, contrary to the observations of Over¬ 
ton and others, that there is no fusion of two distinct spirems as 
the nucleus goes into the first contraction or synapsis. The loose 
spirem condition of the nucleus as it emerges from synapsis is 
followed by a “second contraction” in which a large part of the 
spirem is arranged into loops. The author agrees wit Farmer and 
Moore that each loop represents a bivalent chromosome, the two 
chromosomes having been arranged end to end in the spirem. The 
equational division of the homotype is interpreted as the reappea- 
rance of the longitudinal split which occurred in the first synapsis. 
The chromatin granules (chromomeres) of the spirem as it 
emerges from synapsis are seen to be made up of still smaller gra¬ 
nules. These ultimate granules, — the smallest constituents of the 
chromosomes which can be objectively demonstrated —, the author 
proposes to describe as pangens. There is nothing in the resting 
nucleus that we can look upon as representing a chromosome, for 
all identity of such bodies is lost, ßut the pangens may be regarded 
as retaining their individuality even in the resting nucleus, and as 
being the bearers of hereditary qualities. A. Robertson. 
Senn, G., Die Gestalts- und Lageveränderung der Pflanzen- 
Chromatop'horen. Nebst e|iner Beilage: die Lichtbrechung 
der lebenden Pflanzenzelle. (Leipzig, W. Engelmann. 1908 . 
397 pp. 83 Textfig. 9 Taf. — 20 M.) 
Das Buch enthält eine grosse Fülle von Mitteilungen über 
Form- und Lageverhältnisse der Chromatophoren, die Verf. durch 
sehr zahlreiche und mühsame Untersuchungen gewonnen hat. Nach- 
