342 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
£accharomycetes lose the power of forming spores. This change is 
correlative with others ; e. g. the power of forming films is also lost ; 
and there is more abundant and quicker rate of growth. These newly 
acquired qualities prove to he heritable. 
More recently varieties have been produced in another way and with 
other properties. By cultivating on gelatin, varieties develope having a 
greater fermentative power than the primitive forms. By operating on 
yeast-cells with antiseptics the alcoholic fermentative property has been 
found to be accelerated and strengthened. In these cases, however, only 
transitory transformations are meant. 
Experiments for the purpose of attenuating the fermenting power of 
yeast-cells resulted in a “ constant ” variety. This was obtained by 
making continuous subcultures at 32° without aerating them. The effect 
of the chemical composition of the nutrient liquid is shown by culti- 
vating S. pastorianus in cane-sugar-yeast-water ; after a number of 
generations this yeast loses the power of imparting an offensive odour 
and disagreeable taste. 
Thus there are three important factors in the production of variation 
— the medium, the aeration, and the temperature — the most influential 
being the last. 
Prof. Hansen refers to the experiments of Takamine, Juhler, and 
Jorgensen,* who describe how Saccharomyces cells develope from Asper- 
gillus and Dematium. He remarks that Klocker and Schlonning,j - who 
repeated the experiments, failed to observe any development of yeast- 
cells, and that the whole question must at present still be considered as 
an open one. 
Fertilisation of the Uredinese.J — M. Sappin-Trouffy adduces further 
evidence that the process of impregnation in the Uredinese is strictly 
analogous to that which takes place in the higher plants and in animals, 
especially in the reduction of the number of chromosomes. In a state 
of repose the nucleus has two chromosomes fused into a single mass. 
The multiplication of the nucleus takes place at the extremity of the 
filaments by indirect division perpendicularly to the axis of the tube. 
No reduction in the number of chromosomes takes place before fecunda- 
tion. The peculiarity of the Uredinese is that this reduction occurs 
after fecundation. During fecundation the chromosomes, four in number, 
unite into a single nuclear filament ; the fusion of the nuclear elements 
is always complete; each nucleus contains two chromosomes. When 
the nucleus of the germinating oospore begins to divide, the karyokinetic 
figure, instead of presenting four chromosomes, presents only two. 
Uredinese with Repeated Formation of iEcidia.§ — Herr P. Dietel 
has extended his observations on this phenomenon in the life-history 
of the Uredinese. He enumerates six species of Uromyces and Puccinia , 
in which the germination of secidiospores results in another secidium- 
generation. He states, however, that this is by no means a universal 
phenomenon in the Uredinese ; but that, on the contrary, it is confined 
to those species which have not a perennial mycele, being wanting in 
* Cf. this Journal, 1895, p. 556. f Cf. this Journal, ante, p. 218. 
J Comptes Eendus, cxxii. (1896) pp. 333-5. Cf. this Journal, ante, p. 97. 
§ Flora, lxxxi. (1895) pp. 391-104. Cf. this Journal, 1895, p. 665. 
