Page:Microscopicial researchers - Theodor Schwann - English Translation - 1947.pdf/246

220 REMARKS UPON A STATEMENT a nucleus, and around this again a cell. The accordance in the mode of development of two so different elementary particles, first led to the deduction of the principle of a similar mode of formation for all elementary particles, and then to its proof by observation. Therefore, what we have to decide is, first, whether the idea of comparing an animal elementary structure with a vegetable cell, with reference to a similar mode of development, does occur in Valentin’s earlier observations; and, secondly, whether Valentin has recognised the principle which is contained in the similar mode of development of two elementary particles which, in a physiological sense, are very dissimilar. In my preface I have given a brief historical sketch of the subject from my own point of view, and Valentin’s remarks do not convince me of the necessity of making any alteration in it. Impartiality, however, requires that Valentin’s representation should follow this statement, and I therefore append the passages cited by him, word for word, from his works:

''“In my first histogenetic researches, I observed certain peculiar granules lying in a transparent gelatinous substance, as the primordial matter of all the tissues. I pointed out the difference between these granules in the serous and mucous layers, at the period of the earliest separation of the layers from one another. In the vascular layer I found large globules or cells, which, in respect to their form and juxtaposition, I compared, as early as the year 1835, with vegetable cellular tissue.'' (Entwickelungsgeschichte, 287. The vascular layer seems to be composed of large globules having a mean diameter of 0·001013 Paris inch, which are perfectly transparent in their interior, and so closely crowded together, that they are flattened against one another at many of their points of contact, and assume an hexagonal form like the cellular tissue of plants.) I also first directed attention to the resemblance in form of the cartilages in which ossification was commencing, and particularly (from observations made in conjunction with Purkinje) of the branchial cartilage of the tadpole to the vegetable cellular tissue. (Ib. 209-10. The cartilages of the labyrinth present a variety of form whilst passing through the process of ossification, which differs very essentially from most of the other cartilages of the body, which will be described at greater length presently. In place of the ordinary cartilage-corpuscle, they contain large bodies which are not so well defined in form, most of them furnished with linear boundaries, being roundish,