308 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Nucleated Erythrocytes in Normal Blood.* — Dr. Maurizio Ascoli 

 has made a series of observations on the blood of the dog, with the 

 object of determining the question whether nucleated erythrocytes ever 

 occur in the normal blood of an adult mammal. The blood was taken 

 from the vena efferens tibise immediately after its exit from the bone, 

 and the result was to show the constant presence of a small number of 

 nucleated red corpuscles. The author considers that the observation 

 tends to discredit the common hypothesis that erythrocytes must neces- 

 sarily arise from colourless elements in the adult. 



Erythrocytes and Blood-plates.j — Dr. C. Sacerdotti brings forward 

 evidence in favour of the view that the blood-plates are morphologically 

 independent components of the circulating blood, or, in other words, 

 that they are not secondary derivatives of either red or white blood- 

 corpuscle*. 



Islands of Langerhans in Pancreas.:}: — Dr. V. Diamare has made 

 an elaborate study of the structure and development of these bodies. 

 "What gives his study particular value is that he takes account of the 

 state of affairs in all the main types of Vertebrates. The main con- 

 clusion appears to be that the so-called islands of Langerhans in the 

 pancreas represent a definite and normal kind of tissue, distinct from 

 the zymogenous tissue even from early stages, and similar in nature to 

 the intra- and para-thyroid bodies. 



Intravascular Cells in Capillaries of the Liver.§ — Prof. Browicz 

 has returned to the study of the remarkable cells of the capillaries of 

 the liver which have been already described by him and by Kupffer. 

 Though in broad outline their respective observations are similar, they 

 differ in that Kupffer believes that the cells form a syncytium, and that 

 they constitute an integral part of the capillary wall. The author 

 hardened his preparations in 2 per cent, formalin, and cut frozen 

 sections. By this method he was enabled to demonstrate the existence 

 of cell-boundaries, and to show that the cells form no integral part of 

 the capillary wall, for they are often distinctly separated from it. The 

 function of the cells the author believes to be the production of pigment 

 from engulfed erythrocytes. 



Connective-Tissue of Amphioxus.|| — Dr. H. Joseph distinguishes 

 the following different kinds : — the content of the notochord ; the cellular 

 content of the oral cirri and their basal membrane ; the fibrillar mucilage- 

 yielding connective-tissue in the notochord sheath, &c. ; the gelatinous 

 substance in the fin-rays ; and a tissue (with a strong affinity for picric 

 acid) which occurs in the branchial bars, the velar threads, and the oral 

 cirri. As to the last, he suggests that it may represent the primitive 

 non-cellular state of the cartilaginous skeletal tissue in higher forms. 



Parietal Organ of Lamprey.H — Prof. F. K. Studnicka finds that 

 this is an eye, with an external pellucida and a convex retina. The 



* Arch. Mikr. Anat., lv. (1900) pp. 426-30. 

 t Anat. Anzeig., xvii. (1900) pp. 249-53. 



t Internal Monatschr. Anat. PHys., xvi. (1899) pp. 1-54 (3 pis.). 

 § Arch. Mikr. Anat., lv. (1900) pp. 420-6. 



|1 Arbeit. Zool. Inst. Univ. Wien, xii. (1900) pp. 1-34 (1 pi. and 2 figs.). 

 ^J SB. k. bohmisch. Ges. Wiss., 1899, No. xxxvii., 17 pp. (1 pi. and 2 figs.). 



