摘要:

Summary.1.Parameciumand echinoid larvae under certain environmental conditions swim downwards in light, upwards in darkness. Thus the phenomenon already described by various authors for arthropods exists not only in animals swimming by muscular movements but in organisms moving by ciliary action.2. The phenomenon is reversible.3. The most effective rays are in the ultra‐viole

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1925.tb00550.x

出版商:Blackwell Publishing Ltd    

年代:1925

数据来源: WILEY

摘要:

Summary.The process of cell division in echinoderm eggs has under normal conditions no effect upon the rate of oxygen consumption. If the nucleus plays any direct role in the oxidative processes in the cell it does so independently of any particular phase of nuclear activity. The development of the egg is associated with an acceleration in the rate of oxygen consumption.

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1925.tb00551.x

出版商:Blackwell Publishing Ltd    

年代:1925

数据来源: WILEY

摘要:

Oneof the characteristic features of living cells is that they are permeable to ammonia, but relatively impermeable to caustic soda or caustic potash. The usual method of demonstrating this fact is by staining cells with neutral red. This dye is readily taken up by living cells and is at first diffused through the cytoplasm, which thereby acquires a distinct red colour. At a later stage the dye is usually aggregated into irregular granules. When exposed to dilute solutions of ammonia the neutral red in living cells rapidly becomes yellow, indicating the penetration of the alkali. In NaOH or K. OH the colour of the dye does not change, however, until the cell begins to show obvious signs of degeneration.

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1925.tb00552.x

出版商:Blackwell Publishing Ltd    

年代:1925

数据来源: WILEY

摘要:

Summary.The observed facts as to the permeability of cells to electrolytes account quantitatively for the injury potentials and hydrogen‐ion concentrations of tissues. These can be calculated from their chlorine and water content

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1925.tb00553.x

出版商:Blackwell Publishing Ltd    

年代:1925

数据来源: WILEY

摘要:

Summary.1. The trichocysts are the means wherebyParameciumadheres to surfaces. Adherence takes place whenParameciumare attracted to a particular spot. The cause of this attraction is largely thepH of the water, but it may be masked in certain circumstances.2. The cause of the extrusion of the trichocysts is shown to be slight pressure such as may be set up by theParameciumcolliding with an object in the water. Verworn's view that the trichocyst consists of semi‐liquid material which hardens on being extruded into the water, is here adopted. It can be shown from the experimental evidence that the tip of the trichocyst thread is sticky, but the rest of the thread is not.3. Ciliary motion does not cease whenParameciumis attached by the trichocysts. The speed of movement, which is dependent on ciliary activity, is reduced when the/>H of the water in which the animals are living reaches 80. This reduction in ciliary activity results in the slender trichocysts being able to hold theParameciumfast, when the pH is within 0.1 of 7.9. A further increase in thepH of the water above 8.0 results in the speed of theParameciumbeing so much reduced as to render the force of a collision insufficient to expel the trichocyst. For theParameciumstudied the criticalpH for adherence was 7.95.4. It is shown that the observations of previous workers on the structure of the trichocyst accord very well with their functioning as organs of adherenc

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1925.tb00554.x

出版商:Blackwell Publishing Ltd    

年代:1925

数据来源: WILEY

摘要:

Summary.1. The spermatogonium is a somewhat spindle‐shaped cell with granular mitochondria and a few curved Golgi rods.2. During the growth phase a spermatogonium enlarges into a giant egg‐like spermatocyte.3. Each spermatocyte contains granular mitochondria, a large number of highly curved Golgi elements and curious cytoplasmic fibres which at times attain huge dimensions. Each Golgi rod may have a distinct archoplasmic sphere associated with it.4. In a centrifuged spermatocyte the cytoplasmic fibres are thrown at one end but the mitochondria and the Golgi elements remain uniformly scattered.5. The cytoplasmic fibres are well preserved with Mann‐Kopsch and chromeosmium. They are destroyed to a large extent by fixatives containing acetic acid. Hence all the earlier workers do not figure them.6. The “metaplasm” and the “formations ergastoplasmiques” of Blackman and Bouin brothers respectively are really the Golgi elements which are not completely destroyed by acetic acid.7. During meiosis the mitochondria and the Golgi elements are distributed into two sub‐equal parts.8. When the spermatid is formed most of the Golgi rods assume the form of rings.9. All the mitochondria and the Golgi elements go into the tail of the sperm and directly form the tail sheath.10. The acrosome is probably secreted by a few Golgi rings which get stuck to the anterior face of the nuclear membrane of the maturing sperm. It is very prominent in the ripe sperm.11. A few small granules constantly occur on that portion of the nuclear membrane of the maturing sperm from which the axial filament starts. They are intensely blackened with omit acid and are very probably of t

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1925.tb00555.x

出版商:Blackwell Publishing Ltd    

年代:1925

数据来源: WILEY