AUTHOR’S PREFACE.
in tantam laminam extendatur, nondum satis mihi constat: certe principio increscere volumen cellulze, nescio an imbibitione, constabit, nisi spes fallit, promotis disquisitionibus.” The caution with which Henle (and, indeed, every good physiologist) expresses himself in this passage with reference to the true growth of non-vascular tissues, is the best illustration of the state of the question. There is another observation of Henle’s, which is opposed to the epithelium being regarded as a lifeless substance secreted from the organised tissue; I allude to the passage (1. c. p. 22 et seq.) where he proves that the vibratile cilia, whose motion it is so difficult to explain by physical laws, stand upon little cylinders which are merely a modification of the epithelium.
Turpin (Annal. des Sciences natur. vu, p. 207) showed that the corpuscles, which Donné had found in vaginal discharges, and regarded as cast-off epithelium, were organised cells, and were in general oblong, and either pointed at one or both ends, or altogether irregular in figure, and that a new generation of spherical vesicles[1] took place in their interior. He then remarks (1. c. p. 210): ‘On ne peut s’empécher, aprés avoir bien étudié les vésicules dont est formée la couche de mucus produite par la membrane muqueuse vaginale, d’y voir un tissu cellulaire bien organisé et composé comme tous les tissus cellulaires végétaux, d’un agglomérat, par simple contiguité, de vésicules distinctes et vivant individuellement chacune pour leur propre compte au dépens de eau muqueuse, qui les baigne de toutes parts.” Turpin then compares this tissue of animal cells, presented under the appearance of mucus, with what he calls “ suppurations végétales, excrétions muqueuses, qui semblent suinter sous forme de gouttelettes, de la surface des tissus vifs,’ and which is generally comprised under the
- ↑ May there not have been some confusion here with the nuclei of the epitheliumcells: At present, as far as regards Mammalia al least at least, we know of no formation of cells within cells in the epithelium.
