170 I SUMMARY OF CURRENT RESEARCHES RELATING TO 



and peritoneal linings. According to Bizzozero, it was non-cellular, 

 but Vincenzi brings forward evidence to show that this very delicate 

 membrane always includes cellular elements : — (a) Elements with oval 

 nucleus, sparse cytoplasm, and very fine prolongations of considerable 

 length, and (6) flat elements, finely granular, very transparent, and very 

 irregular in outline. These cells are not numerous, but they are never 

 absent. They form the most superficial stratum — an extremely delicate 

 stratum — of the underlying supporting tissue. 



Filamentous Tufts of Epithelial Cells in Vas epididymis of Man.* — 

 Dr. A. Gurwitsch describes the remarkable Haarbilschel which vary in 

 form according to the condition of the secretory process. The fluid 

 •or semi-fluid secretion of the cells is got rid of via the tufts, and the 

 internal ends of the tuft-filaments, which go deep down into the cell, 

 have to do with the accumulation and breaking up of the secretion. 



The author shows that the plasmic threads which project, apparently 

 without sharp boundary, from the free surface of the cells, which one 

 might on account of their motor changes be inclined to call genuine 

 pseudopodia of the epithelial cells, retain their individuality deep within 

 the cell-substance, and form a structure quite distinct from the surround- 

 ing cytoplasm. 



The " diplosomes " (Zimmermann) associated with the tufts suggest 

 centrosomes in several respects, but as no direct role in mitosis has been 

 demonstrated, the identification lacks security. If they are equivalent 

 to centrosomes, then it would be necessary to credit centrosomes with 

 some role in connection with the form-changes associated with the 

 secretory process. 



What are "Blood-plates" ?f— Dr. Ernst Schwalbe gives a critical 

 account of the different positions held on this question, and on the basis 

 of his own researches sums up as follows : — There is no doubt that the 

 blood-plates of most authors are derivatives of red blood-corpuscles, and 

 to a smaller extent of white corpuscles. They stand in intimate rela- 

 tion to the phenomenon of coagulation, and bring about the morpho- 

 logical dependence of the blood-corpuscles and the clotting. Among 

 the plates are some with and some without haemoglobin, often there is 

 an internal body which can be differentiated by means of hematoxylin. 

 Blood-plates are not homologous with the spindles of the frog's blood. 

 It is possible that in addition to the kind of blood-plates described above, 

 another kind, not derived from degenerating corpuscles but pre-existent, 

 is found in the blood, but there is as yet no positive evidence in support 

 of such a view, and such evidence can only be looked for by a study of 

 the embryology of blood. 



c. General. 



History of Medicine and Biology in the Nineteenth Century.! — 

 Dr. F. C. Muller has written a very successful historical sketch of the 

 progress of Anatomy, Physiology, Embryology, Bacteriology, Medicine, 



* Arch. Mikr. Anat., lix. (1901) pp. 32-62 (1 pi. and 1 fig.). 



t Anat. Anzeig., xx. (1901) pp. 385-94. 



J Gescliichte der organischen Naturwissenschaften im neunzelmten Jahrhundert. 

 Medizin und deren Hilfswissenschaften, Zoologie und Botanik, Berlin, 1902, Svo, xv. 

 and 714 pp. and 16 portraits. 



