188 SUMMARY OF CURRENT RESEARCHES RELATING TO 



b. Histolog-y. 



Culture of Tissues outside the Organism. — Montrose T. Burrows* 

 has cultivated dissected tissues of a GO-hour chick in a plasma derived 

 from the adult. In this he followed Ross Harrison's lead. Skin, nerves, 

 and mesenchyme-cells flourished well. Nerve-fibres grew for three or 

 four days. A heart continued to beat for eight days. The growth of 

 nerve-fibres was especially studied. 



Alexis Carrel t and Montrose T. Burrows have succeeded in cultivat- 

 ing in plasma all sorts of adult tissues from cat and dog. Their 

 experiments included connective-tissue, cartilage, marrow, skin, peri- 

 toneum, spleen, kidney, thyroid, supra-renal, ovary, lymphatic ganglion. 

 Abundant karyokinesis occurred. 



J. Jolly | has succeeded in keeping Batrachian leucocytes alive for 

 ten months. 



Blood-formation in Grass Snake.§ — Wera Dantschakoff finds that 

 the erythropoesis in Tropidonotus natrix occurs during the greater part 

 of embryonic life in the blood vessels associated with the yolk-sac. At 

 the end of embryonic life a new blood-forming organ develops, namely 

 the medulla of the bones, which in the grass-snake is localized in the 

 vertebras. Here, as in the chick and other forms, the first free cell, the 

 lymphoid hasniocytoblast, develops in loco from mesenchyme-cells ; and 

 from its many-sided differentiation arise all the different cells of the 

 blood. 



Endothelial Genesis of Leucocytes. || — Vincenzo Patella has made 

 a prolonged study of the genesis of the mononuclear leucocytes, and has 

 come to the conclusion, which, if correct, is very important both 

 theoretically and practically, that they arise from detached endothelial 

 cells of the blood-vessels. This conclusion, he notes, was also reached 

 by Tigri so long ago as 1857. 



Giant-cells of Mole's Placental — A. van Cauwenberghe finds in 

 the placenta of the mole a set of cells comparable to the megacaryocytes 

 of haematopoietic organs, in their genesis, in their repeated pluripolar 

 nuclear divisions, and in their fate or cytolysis. But the megacaryocytes 

 arise from white blood corpuscles, these placental giant-cells from 

 decidual connective-cells. The megacaryocytes disintegrate to nourish 

 the erythroblasts ; the placental or decidual giant-cells elaborate certain 

 substances characteristic of the blood-plasma during gestation. 



Chordoid Tissue.** — Joseph Schaffer distinguishes diffuse and com- 

 pact chordoid supporting tissue. Under diffuse chordoid supporting 

 tissue he discusses the vesicular connective substance in Molluscs and in 

 Decapod Crustaceans, the vesicular tissue of the Tunicate test, the 

 perimeningeal filling tissue in Ammoccete and lamprey, the vesicular 

 tissue near the eye of the hag, the chordoideal tissue of Petromyzon 



* C.R. Soc. Biol. Paris, lxix. (1910) pp. 291-2. 

 t Tom. cit., pp. 293-4. J Tom. cit., p. 295. 



§ Verh.-Anat. Ges. (1910) ; Anat. Anzeig. Erganz., xxxvii. (1910) pp. 70-75. 

 || La Genese Endothi-liale des Leucocytes Mononucleaires du Sang. Sieni e, 

 1910, 242 pp. (113 figs.). 1 Arch. Biol., xxv. (1910) pp. 99-168 (4 pis.). 



** Zeitschr. wiss. Zool., xcvii. (1910) pp. 1-90 (2 pis.). 



