The microscopic organisms found in the blood of man and animals, and their relation to disease / By Timothy Richards Lewis.
- Timothy Richards Lewis
- Date:
- 1879
Licence: Public Domain Mark
Credit: The microscopic organisms found in the blood of man and animals, and their relation to disease / By Timothy Richards Lewis. Source: Wellcome Collection.
Provider: This material has been provided by London School of Hygiene & Tropical Medicine Library & Archives Service. The original may be consulted at London School of Hygiene & Tropical Medicine Library & Archives Service.
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![or a cleft form. This is a subject which has formed the subject of debate during the last sixteen years, and many observations have been recorded for the purpose of shewing that, as a result of cultivation-experiments, the most opposite forms have been seen to pass from one into the other.' With reference to this point Nageli forcibly points out the fallacies to which men are liable in drawing conclusions from cultivation-experiments, and says that, in many respects, it would be as rational for the husbandman to assert that the weeds in his field were the result of transformations which the seed of wheat previously sown had undergone. No one would believe such a statement, for the seeds of weeds are large enough to be easily recognised, whereas the germs of fungi are of microscopic dimensions—those of the schizomycetes often barely distinguish- able with the highest powers: hence the assertions which have been made regarding the transition of such minute organisms cannot easily be controlled. ' Moreover,' adds Nageli, 4 the rapid and superficial observer has a marked advantage : the conclusions which he has arrived at as the result of a so-called uncontaminated cultivation [Reinkultur] of a single week's duration may require years of labour on the part of the thoroughly competent observer to disprove.' This question has of late years been investigated by many distinguished The limited range of transform- *™™**> notably by Professor de Bary of Strasburg. ations among fungi. He ^Q shewn that a fungus undergoes but a very limited and well-defined range of changes. Nageli, as the result of his own observations, declares that, of the three groups of fungi above referred to, the f mould' and f sprout' fungi are closely related, but that, with one excep- tion, they have not yet been seen to pass from one form into the other. The exception consists in the circumstance that a certain species of mucor (a mould) has been observed to present the two forms of vegetation—the filamentous and the sprouting. Fission-fungi, however, do not The schizomycetes distinct from . . matether sroupa and do not germ stand in any genetic relation to either of the other two groups, for they neither give rise to other fungal forms nor originate from them: hence it is distinctly laid down that they do not germinate. In this it would appear that Nageli and de Bary are com- pletely in accord. Nageli states that it is comparatively easy to demonstrate that the ' fission' group of fungi are not transformed into other groups from the circumstance that members of the latter when present in a solution are killed](https://iiif.wellcomecollection.org/image/b2136414x_0017.jp2/full/800%2C/0/default.jpg)
