18 SUMMARY OF CURRENT RESEARCHES RELATING TO 



structures as tho intra-nuclear, and stand in direct connection with 

 them. They may be stained with eosin and safranin, or with hema- 

 toxylin. Like the intra-nuclear structures, they may bo isolated, or 

 united in complex systems. The following main types may be dis- 

 tinguished: — (a) plasmosomata (stained with eosin and safranin); 

 (b) karyosomata (stained with hamiatoxylin) ; (c) achromatic granules 

 (forming all sorts of chains, circlets, and aggregates) ; (d) combinations 

 of (a) and (<?) ; (e) combinations of (b) and (c) ; (/) combinations of 

 (rt) and (6), combinations of (a), (b), and (c) ; (Ji) combinations of sickles 

 and spheres, rich in eosino- and safranophilous substances, but also 

 plus colourless elements ; (i) similar combinations, staining dirty violet 

 or deep blue ; (/) combinations of sickles and spheres with finely 

 granular protoplasmic masses ; (A-) nucleus-like structures containing 

 various forms of the above ; (I) zymogen granules (stained with eosin 

 and safranin) ; (mi) combinations of (I) with (a) ; (w) combinations of (Z) 

 with (c^l ; (o) mucinoid spheroids ; (p) combinations of (o) with (a), &c. ; 



(5) combinations of (0) with (Z). Surely enough of permutations and 

 combinations ! Several may occur both as intra- and extra-nuclear, viz. 

 a, b, c, d, e, f, and g. The others are wholly extra-nuclear, though they 

 may be in special indentations of the nucleus. 



(3) The above types occur constantly, and must express definite 

 structural relations. The variations are always quantitative, the 

 fundamental structure is constant. 



Nuclei of Muscle-cells.* — Dr. S. M. Lukjanow, continuing his 

 contributions to cellular morphology, has investigated the nuclei of 

 unstriped muscle-cells in Salamandra maculata. 



As regards form, the following types of muscle-nuclei have to be 

 distinguished : — (a) Eegular cylindrical rods rounded at the ends and 

 curved when elongated ; (Z>) S-shaped, doubly or trebly curved ; (c) 

 6pirally coiled, with 2, 3, 4, or more twists; (d) spindle-shaped ; (e) like 

 those of cylindrical epithelium, round or oval in optical section. The 

 size varies greatly, and is exposed in a series of tables. The staining 

 properties are also very diverse even in the same section, and there was 

 no relation between these variations and those of size. 



Internal Structure. — The presence of hyaline vesicles or achro- 

 matic portions is noted. They form chains within the nuclei. Fine 

 chromatin granules are seen at the poles of contact, and also at times 

 peripherally. The author distinguishes with combined staining the 

 following kinds of nuclear corpuscles : — (a) The so-called plasmosoniata ; 



(6) the so-called karyosomata ; (c) elements of a mixed character. The 

 various forms and sizes are noted. 



Disposition. — The nuclei may (1) lie parallel to one another, or 

 (2) in rows one behind the other. In the chain arrangement, the rows 

 may consist (a) of two members of similar appearance ; (b) of more than 

 two members which are not uniform ; and (c) of one large rod or 

 spindle-shaped nucleus which bears a much smaller but similar nucleus 

 at one of its poles. 



Cell-di vision.! — Herr F. Tangl has studied the exact connection 

 between the nucleus and the body of the cell during mitosis, and comes 

 to the two following main conclusions : — 



(1) With the dissolution of the achromatic nuclear membrane the 



* Arch. f. Mikr. Anat., xxx. (1887) pp. 545-58 (2 pis.). t Ibid., pp. 529-45 (1 pi.). 



