566 SUMMARY OF CURRENT RESEARCHES RELATING TO 



j3. HistologT.* 



Karyokinesis.j — Prof. W. Waldeyer gives a useful historical resume, 

 witli interj^olated criticisms, of recent researches on cell-division, with 

 accompanying diagrams and bibliography. 



Cup-shaped Cells. | — M. L. Eanvier discusses the vacuoles of cup- 

 shaped cells, the movements of the vacuoles and the intimate phenomena of 

 the secretion of mucus, taking as his object of investigation the cells 

 found in the epithelial covering of the membrane which invests the retro- 

 lingual lymphatic sac of the edible or the grass-frog. In answer to the 

 question. Is the vacuolar movement a vital one ? M. Eanvier finds that it 

 ceases on the death of the cells. After staining, it is possible to see that 

 the vacuoles are situated in the mass of protoplasm which occupies the base 

 of the cell, or in the protoplasmic processes which are given off from it, 

 and they may, therefore, be found in any region of the cup-shaped cell 

 from its base to its orifice. When the cells are examined in the living 

 state it may be noticed that some of the vacuoles which they contain dis- 

 appear more or less rapidly and before reaching the surface of the mucous 

 membrane. It is probable that, breaking within the cell, they pour out, 

 along the lines of protoplasmic substance, the liquid which they contain, 

 and that this liquid, bathing the masses of mucigen, carries away part of it. 

 Thus charged with mucin it arrives at the surface converted into mucus. 



Giant Cells of Tuberele.§ — Herr A. Obrzut concludes, from his 'obser- 

 vations, that a giant tubercular cell does not represent a histological unit, 

 but in reality a conglomeration of endo- or epithelial cells hypertrophied by 

 the influence of the parasites of the tuberculosis, and that it is, as usually 

 observed, in process of undergoing retrogressive modifications. 



Alteration of the Red Blood-corpuscles. |1 — In normal blood Sig. A. 

 Mosso finds corpuscles which become altered with the greatest ease, while 

 others are more resistant. It is impossible to examine microscopically the 

 blood of most animals without destroying or profoundly altering a certain 

 number of corpuscles. Mere contact with glass sufiices to quite decolorize, 

 alter their shape, and bring the nucleus into view. In the red corpuscle can 

 be distinguished a skeleton or network, which is brought out by maceration 

 and digestion. By digesting the blood of various animals, especially birds, 

 in gastric juice, a red corpuscle is seen to be composed of an external 

 envelope, of a granular fibrillar network, and of a nuclear sue. Within the 

 nuclear sac are usually seen ten to twelve corpuscles, which stain more 

 deeply than the nucleus. Between the external envelope and the nucleus 

 may be distinguished, even in mammals, a median zone, which the author 

 calls the cortical part. It is composed of two substances so intimately 

 commingled that they form a homogeneous substance in the physiological 

 condition, but which separate on alteration of the corpuscle, and then the 

 one looks transparent and the other yellow from haemoglobin. Sig. Mosso 

 has seen crystals within the corpuscles of dog's blood, coagulated slowly 

 or rendered incoagulable by the addition of pancreatine. These crystals 

 are rhomboidal, with well-marked angles, and yellow in colour, and con- 

 centric in position. The diameter of the corpuscles being about 6 or 7 /x, 

 the crystals measure 2 • 5 ^u, to 5 /x. The resemblance of these crystals to 



* This section is limited to papers relating to Cells and FiVires. 



t Arch. f. Anat. u. Physiol., 1887, pp. 1-30. 



i Comptes Eendus, civ. (1887) pp. 819-22. 



§ Arch. Slav. Biol., ii. (1886) pp. 402-25 d pi.). 



II Atti R. Accad. Lincei.— Rend., iii. (1887) pp. 252-7. 



