this purpose chiefly a solution of one part of nitrate of silver in 120 parts of distilled water ; and sometimes also the chromic acid. He admits that the use of these reagents would, on account of their destructive tendency when concentrated, be objectionable as proofs of the absence of any visible structure ; but as the point to be proved is that a certain specific structure does exist, he contends that the same appearance would not equally result from the chemi- cal actions of reagents so different as are those of chrome and the salts of mercury and of silver. After the appearance of the fila- ment, thus brought to light, has become familiar to the eye, it may be discerned in the blood-discs, when coagulation has commenced, without any addition whatever. Those blood-discs of the newt, which contain filaments, often assume the form of flask-like vesicles, the membranes of which exhibit folds, converging towards the neck, where, on careful examination, a minute body may be seen pro- truding. This body is the extremity of the filament in question, its protrusion being occasionally such as admit of its remarkable struc- ture being recognised.
The author proceeds to describe various appearances which he has observed in the coagulum of the blood, and which strongly re- semble those met with in the tissues of the body, and are obviously referable to a similar process of formation. He bears testimony to the accuracy of the delineations of coagulated blood given by Mr. Gulliver. One of the most remarkable phenomena discovered by the author in the coagulation of the blood is the evolution of red colouring matter ; a change corresponding to that which he had previously observed to take place in the formation of the various structures of the body out of the corpuscles of the blood. He con- siders the production of filaments as constituting the essential cir- cumstance in coagulation.
He conjectures that the notched or granulated fibres noticed in the blood by Professor Mayer, may have been of the same kind as the flat, grooved, and compound filaments described by himself ; but he thinks that, in that case, Mayer's explanation of their mode of origin must be erroneous ; for they may be seen to be produced by a portion of the blood not mentioned by him, namely, the corpus- cles.
Mr. Addison's discovery of globules in the uppermost stratum of inflammatory blood, and of their influence in the formation of the buffy coat, is confirmed by Dr. Barry, who remarks that these glo- bules are altered red blood-discs. That the blood corpuscles are reproduced by means of parent-cells, as suggested by Mr. Owen and by the author, is confirmed by the observations of Dr. Remak ; but the author had long ago indicated a division of the nucleus as being more particularly the mode of reproduction, not only of those corpuscles, but of cells in general. With this conjecture the obser- vations of Remak on the blood-corpuscles of the foetal chick fully accord. Whether the author's further speculation, namely, that the parent-cells are altered red blood-discs, is correct, still remains to be seen.
