Observations on the development of the blood corpuscles in the chick, with the various changes which they present from their first appearance to their full development : with some remarks on these changes / by William Macleod.

Date:
[1842]
Catalogue details

Licence: Public Domain Mark

Credit: Observations on the development of the blood corpuscles in the chick, with the various changes which they present from their first appearance to their full development : with some remarks on these changes / by William Macleod. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    egg ; and the appearances which the blood corpuscles presented in all these situations, were the same, provided the two last structures were examined at the proper time ; for if the exami- nation is made very early, the oval appearance of the blood cor- puscles will not be seen, as they do not take this form until after the fourth day.^ By examining the blood in these different ways, I hoped to be able to remove all chance of fallacy. I shall divide the following description into three stages. In the first, the different changes which the blood corpuscles pre- sent from their first appearance, until their central part has be- come granular. Second, from the gradual disappearance of this granular structure, to the flattening of the sides of the corpuscle. And, thirdly^ the changes which they present whilst passing from the circular to the oval form. First Stage.—On placing the bloodremoved in the manner above described under the microscope, a number of small granules are seen floating about in the field ; these enlarge and become clearer in the centre ; this enlargement goes on very rapidly, and when they have gained to about twice their original size, the central clear part becomes dull. This dulness slightly increases, and in a short time it is seen to be distinctly granular, whilst the bor- ders are observed to be well defined, smooth, and clearer than the central part. The enlargement of these bodies, with the granular appearance of their centre, seems not to depend on the aggregation of granules round a central one, but on a property which they have in themselves of enlarging and of presenting that figure. In the field, a number of these objects are fre- quently seen close together, and many of them appear more granular than the rest. During all this time they are quite spherical, and are of good consistence, as they do not lose their form by considerable pressure. Second Stage.—The central portion becomes gradually less opaque, and gradually ceases to appear granular, the external por- tion at the same time separating in some degree from the central part. This part I shall subsequently call nucleus. The blood cor- puscle in this stage of development has the appearance of a slight- ly flattened round cell, formed of a somewhat delicate but elastic membrane, with a nucleus in the centre. At this time, a num- ber of these bodies, being close to each other in the field, present a yellowish colour. This colour seems to me to I’eside in the space between the nucleus and membrane. Of this, however, I * The time of this appearance, however, varies much in different chicks, as also does the time of the apjieai’ance of the different structures and organs. ThU is not the effect of any external cause, as it is observed when the eggs are put into the liatching house at the same time, and removed together after having lain there for a certain period, and when consequently all external circumstances must have been the same to each and all of them.