Pure Cultivation of Yeasts.-The methods which were first adopted by Hansen for obtaining pure cultures of yeast were similar in principle to one devised by J.
Only those cultures which contained a single yeast speck were assumed to be pure cultivations.
Industrial Plants.s T he manufacture of sugar from beetroot, owing to the increased~use of sugar, became highly important during Cultures -industriellesUnder this head the French group beetroot, hemp, flax and other plants, the products of which pass through some process of manufacture before they reach the consu mer.
In early inquiries a great point was made of the prevention of putrefaction, and work was done in the way of finding how much of an agent must be added to a given solution, in order that the bacteria accidentally present might not develop. But for various reasons this was an inexact method, and to-day an antiseptic is judged by its effects on pure cultures of definite pathogenic microbes, and on their vegetative and spore forms. Their standardization has been effected in many instances, and a water solution of carbolic acid of a certain fixed 'strength is now taken as the standard with which other antiseptics are compared.
But by a process of successive and continued artificial cultures under different conditions, the virus of the organism is found to become attenuated; and when this weakened virus is administered, the animal is rendered immune against further attacks.
- According to a conception of the world frequently found among peoples of the lower cultures, all the affairs of life are supposed to be under the control of spirits, each ruling a certain element or even object, and themselves in subjection to a greater spirit.
Long before history begins, however, the cultures of Eridu and Nippur had coalesced.
But in the admixture of the two cultures the influence of Eridu was predominant.
Pure cultures may be made and after dilution in water or other liquid can be mixed with soil to be ultimately spread over the land which is to be infected.
More or less pure cultures of the nitrogen-fixing bacteria belonging to the Azotobacter group have been tried and recommended for application to poor land in order to provide a cheap supply of nitrogen.
The application of pure cultures of bacteria for improving the fertility of the land is still in an experimental stage.
Experiments show that pure cultures, when mixed with garden soil constantly moistened short of saturation and kept in the dark at a temperature of 14° C., will retain their vitality for more than ten months; from moist soil kept at 26° C. they die out in about two months; from moist soil at 30° C. in seventeen days; and in dry soil at the same temperature within a week.
Cultures of the typhoid organism planted at a depth of 18 in.
The organization of the French colonies, though industrially ruinous, gave them Illustrations representative of the primitive cultures of Central America, Mexico and Peru (q.q.v.) selected and arranged by Dr Walter Lehmann of the Royal Ethnographical Museum, Norwich.
The most favoured areas were those where corn and other plants could be artificially produced, and there barbaric cultures were elaborated.
Schuppan has shown that it is possible to produce good butter from Pasteurized or even sterilized cream, and Weigmann introduced the plan of artificially souring cream by means of pure cultures of B.
P. donovani in cultures of different ages.
Nevertheless, the general appearance and structure of these motile forms so greatly resemble that of a Herpetomonad, or of the " pseudo-Herpetomonadine " forms of a Trypanosome which are obtained in cultures, that it cannot be doubted that the " Leishman-Donovan-Wright " bodies are closely connected with the Haemoflagellates.
In favour of the conidial view is the fact that in the case of Collema and a few other forms the spermatia have been made to germinate in artificial cultures, and in the case of Calicium parietinum Moller succeeded in producing a spermogonia bearing thallus from a spermatium.
The work is carried on from October till the end of March and April, after which, with the exception of melons, the cultures are carried on in the open air.
The group has attained an importance of late even beyond that to which it was brought by Pasteur's researches on alcoholic fermentation, chiefly owing to the exact results of the investigations of Hansen, who first applied the methods of pure cultures to the study of these organisms, and showed that many of the inconsistencies hitherto existing in the literature were due to the coexistence in the cultures of several species or races of yeasts morphologically almost indistinguishable, but physiologically very different.
The principal cultures are tobacco, maize and cotton, and the mulberry for silk production.
For the mainland cultures a new term " Helladic " has lately been invented, and three chronological divisions, Early, Middle and Late Helladic, are proposed to correspond with the parallel Cycladic and Minoan periods.
What is chiefly sought by such revision is better evidence for the chronology and inter-relation of the different cultures, but much new information has been gained in regard to plan and structure of the palaces and fortifications of Mycenae and Tiryns.
After a lengthy development in the history of the human race a definite stage seems to have been reached about 5000 B.C., which step by step led on to those great ancient cultures (Egyptian, Aegean, Babylonian) which surrounded Palestine.
Just as ancient cultures used creation myths to explain their beginnings, we have stories of the "American Experience" that we tell again and again until they acquire mythic status.