ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
499 
conditions must be taken into account in order to explain the causes of 
these variations. The nuclear divisions in the vegetative tissue of the 
apex of the stem and root follow the ordinary course, and are described 
in detail ; as are also the processes in the periderm formed as the result 
of injury to the tuber. The development of the achromatic fibres corre- 
sponds in many respects to that described by Mitzkewitsch * * * § in the case 
of Spirogyra. It is monaxial and acentric, there being no indication of 
an extra-nuclear centre. During the whole of the division the fibres 
which run to the pole at no time unite into a single point, but all 
develop from the first in the direction of the division-axis. 
The differences between the two kinds of nuclear division in the 
potato chiefly relate to the development of the achromatic figure. While 
in the apex of the stem or root a hyaline periplast arises of bipolar 
form, on the periphery of which are formed fibres which run meridionally 
round the nucleus ; in the divisions, on the other hand, on the surface 
of a wound to the tuber, the fibres grow directly from the surface of the 
nucleus, both under normal conditions and when the cells are subjected 
to strain or pressure. As a rule, the number of chromosomes in the 
figures is greater in the latter than in the former case. 
Artificial Production of the Sickle-stage of the Nueleole.f — Mr. 
J. H. Schaffner, after using the following mixture : — alcohol 95 ccm., 
chloroform 5 ccm., glacial acetic acid 1 ccm., chromic acid 1 per cent. 
1 ccm., for killing the root-tips of the common onion, found that the 
cells were badly shrunken, the nuclei displaced, and the cytoplasm 
more or less distorted. Nearly all the nuclei of the cells of the peri- 
pheral layers showed the sickle -stage. In the central cells there was 
little displacement, though the cells were much shrunken. 
The inference from the foregoing facts is that the sickle-stage is an 
artificial production. 
(2) Other Cell-Contents (including* Secretions). 
Aldehyd in Green Leaves.^ — Prof.; J." Reinke and Herr E. Braun- 
miiller have carried on a series of experiments on different plants to 
determine the effect of light on the amount of [formic] aldehyd con- 
tained in green leaves. The results were not uniform ; but the general 
conclusion was that, in most cases, deprivation of light caused a distinct 
diminution in the amount of aldehyd. The test employed was precipi- 
tation by metanitrobenzhydrazid. The authors conclude that aldehyd 
is probably not the first product of assimilation, but that, whatever this 
may be, it is, in the majority of cases, first condensed into sugar, in 
other cases into “ leaf-aldehyd.” 
Origin of Storax.§ — Herr J. Moeller, who has been occupied for the 
past twenty years in studying the origin and development of storax, 
recently showed that this balsam is not produced in the bark, but is 
formed in the wood ; that it is not a physiological secretion, but a patho- 
logical product which arises after damage to bark or wood. 
* Cf. this Journal, 1898, p. 567. 
f Journ. Applied Microscopy, ii. (1899) pp. 321-2 (8 figs.). 
% Ber. Deutsch. Bot. Gesell., xvii. (1899) pp. 7-12. 
§ XII. Congres Internat. d. Med. a Moscou, sect. iv. See Centralbl. Bakt. u. 
Par., 2* e Abt., v. (1899) p. 412. 
