402 Journal of Applied Microscopy. 



chromatic thread. Later this undergoes all the changes seen in the karyokinesis, 

 and in the stages of the daughter skein the central chromosomes become the 

 nucleolus and the peripheral the nuclear membrane. 



Lukjanow describes the follicle cells of the testis of the intestinal parasite of 

 the dog, and says : The nucleolus consists typically of three parts, a middle 

 part which, on double staining with haematoxylin and safranin, takes the red 

 stain and appears elipsoidal. Two markedly larger end pieces stain a dark or 

 violet red. J. Wagner, in studying the spermatogenesis ot the spider, describes 

 two kinds of nucleoli, one large and genuine, and two smaller and false. The 

 first divides independently of the chromosomes, and often not at the same time ; 

 the second take part in the formation of chromosomes. 



Strasburger, in botany, studying the centrosome and spindle formation, dis- 

 tinguishes in protoplasm two kinds of substance, thread-like " kinoplasm " and 

 alveolar " trophoplasm." In recent publications he considers the nucleolus as a 

 reserve material for the formation of the spindle and the nuclear membrane. 



Mitzkewitsch, studying karyokinesis in spirogyra, says that the whole mass 

 of chromatin is in the form of a spheroidal nucleolus. At the beginning of 

 karyokinesis uneven staining power is shown, chromosome granules appear, and 

 a surrounding pale substance, containing fibers that pass out into the colorless 

 threads of the protoplasm. The darkly staining part forms the chromosomes, 

 and the fibrous part the spindle of the karyokinetic figure. On a return of the 

 resting state, the nucleolus reappears from the chromosomes and spindle threads. 



Czermak himself found earlier that the resting nucleus in the segmenting egg 

 of the salmon contained a very large spherical nucleus. Fixation was princi- 

 pally in a mixture of one-fourth per cent, chromic acid, one-half per cent, acetic 

 acid, and one per cent, platinum chloride, with many others also. Staining was 

 according to Fleming, or with Haidenhein's iron hematoxylin. After Fleming's 

 orange stain and overstaining wifh gentian, the nucleoli were almost black, the 

 chromosomes violet, the yolk granules red, and the protoplasm golden yellow. 

 Shortly summarizing his results, the author finds that the nucleoli in the material 

 studied disintegrate into (chromatin granules) an oxychromatic network and a dark 

 substance (in the salmon), and also take part in the formation of chromosomes, 

 and probably the spindle fibers. The disintegration appears to go on so that at 

 first an oxychromatic substance rises, probably, from the fibers of the spindle in 

 which the chromatic substance and probably the dark material afterwards is 

 absorbed. a. m. c. 



Hoffmann, Dr. R. W. Zur Orientirungkleinster A mixture is used consisting of equal 

 mikroscopischer Objecte. Zeits, f. wiss. parts of clove oil and CoUodion, which 

 ' "^^ * -^ " -^ ' ^^* is left in a wide-mouthed bottle in an 



exposed place for twenty-four hours. Afterward the mass is placed in xylol, 

 where it becomes transparent. Objects in this mass are placed on glass slips 

 about two, or two and one-half cm. long, by one-half, or three-quarters cm. wide, 

 and oriented by means of currents produced by drawing a needle through the 

 mass. The glass slip gives a perfectly level surface, and the stained specimen 

 may be seen as clearly in this medium as a fo/o mount in balsam. Orientation 



