ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
189 
BOTANY. 
A. GENERAL, including- the Anatomy and Physiology 
of the Phanerogamia. 
o. Anatomy. 
CD Cell-structure and Protoplasm. 
Attraction-spheres and Centrosomes.* — Mr. J. H. Schaffner finds 
the following objects especially favourable for observing attraction- 
spheres and centrosomes: — young root-tips and resting-cells of the 
epiderm of old bulb-scales of Allium Cepa ; resting-cells of the root-tip 
of Vicia Fdba ; root-tips of Tradescantia rosea ; epiderm of the anther 
and ovary-walls of Lilium longiflorum. As the general result of his 
observations he concludes that centrosomes and attraction-spheres are 
present in non-reproductive as well as in reproductive vegetable cells ; 
that they- remain on the outside of the nucleus during its resting stage ; 
and that they persist in cells which have ended their growth and division. 
He further states that in Phanerogams there are two of these bodies for 
each resting nucleus. During impregnation there is a union of those 
attraction-spheres and centrosomes which accompany the male nucleus 
with those of the female nucleus. The bodies migrate and divide, and 
are thus carried from one cell to another throughout the entire organism, 
whether plant or animal. 
Structure of the Cell-wall.f — Herr C. Correns has undertaken a 
series of investigations on the structure of the cell-wall in different 
organs, and in a great variety of plants belonging to different divisions 
of the vegetable kingdom, especially in reference to the three following 
statements by Wiesner : — that the cell-wall contains protoplasm as long 
as it is in a condition of growth ; that the cell- wall is, up to a certain 
period, a living structure, and its growth an active one ; and that the 
cell-wall is composed of definite particles, the dermatosomes. 
The use of all the various reagents for protoplasm has convinced 
Correns that in no case can the presence of this substance in the cell- 
wall be asserted with certainty (except in the case of enclosed particles 
or of connecting strands); while in the great majority of cases it is 
certainly absent. The substance which has been mistaken for proto- 
plasm is tyrosin, or some other imperfectly known substance. In no case 
could a superficial growth of the cell-wall be due to the presence in it of 
protoplasm. There is no essential chemical difference between the 
dermatosomes and the substance which unites them together; in no 
case could the formation of the former out of plasomes or microsomes 
be determined. The red stain produced by Millon’s reagent in lignified 
cell-walls is due not to the presence of vanillin, but probably to that of 
tyrosin. 
* Bot. Gazette, xix. (1895) pp. 445-59 (1 pi.). 
t Jaln-b. f. wiss. Bot. (Pringslieim), xxvi. (1894) pp. 5S7-673 (1 pi. and 2 figs.). 
Of. this Journal, 1892, p. 222. 
