Annals of botany by IDEAL (Project)

Author:IDEAL (Project)
Language: eng
Format: epub
Tags: Botany, Plantkunde, Botanique
Publisher: London, New York [etc.] Academic Press [etc.]
Published: 1887-03-25T05:00:00+00:00

Ellis. — The Life-history of Bacillus hirtus.

whole mass suddenly separated into its component parts, and each al began a separate existence. This naturally caused them to tVfc:<ir from the microscope-field. From the data here supplied, the necessary for a single complete division from beginning to end was 3 ^"° = 25 minutes. 7 If we bear in mind how short a time it takes for an Agar surface completely covered with a thick growth when it has only been mated at a single point, it must often happen that a complete division i place in less time even than twenty-five minutes.

Development of Spores.

jserve the formation of spores, material was taken from a three

.alture, in which, as a general rule, a number of spores of all ages

le microscope-field, and there will usually be a lai^e number of

uals showing the early stages of development. Meyer's stain (10)

for nuclear coloration does very well for the first stages of spore-

ipment, but it is necessary to modify the method, so far as the

niity of stain to be used is concerned. The method which I employed

isist-; In fixing the material for three or four minutes in a drop of Forraol,

ig by adding to the Formol a few loopfuls of a solution made up

as i< ns:—

3 C.C. ale. sat. solution Fuchsin. loc.c. abs. ale. 10 C.C. HaO. Sometimes it will be found advisable to dilute the Formol with water. With regard to the number of loopfuls of the stain which will be required, that must be tested in each individual case: sometimes good results are obtained by using four or five loopfuls to the drop, and examining after four minutes. At other times, especially when the drop is comparatively small, we can use less of the stain, and examine after a longer interval. Again, results quite as good can be obtained by using other stains, e. g. Methylene-blue. A good stain can be obtained by mixing i ex. of a saturated alcoholic solution of Methylene-blue and 40 c.c. of water. Care must be taken that the drop containing the material does not dry up, otherwise accurate observation of young spores is impossible. The first stage in the development is seen in the formation of a clear oval area in the interior of the cell (Fig. 55). This space is of the same size as the mature spore, and represents, as it were, the site that will be occupied by it. This space is clearly marked off from the surrounding cytoplasm, but this depth of staining does not differentiate the cytoplasm from the wall. In one instance I observed 13-15 ^^^ attached together, all of which were at this stage of development. In each

clear space a round spot was visible, from which in one or two cases slight radiations were observable (Fig. 36). This I take to be the nucleus, surrounded by cytoplasm, which thus makes it a fairly prominent object. I did not see a single case in which more than one of these round objects was

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