1884.] 59 [Hyatt. 



of the spontaneous division of cells. According to the exten- 

 sive researches of La Yalette St. George the mother cell or 

 spermatocyst is apt to divide into two parts, one of which even- 

 tually subdivides into spermatozoa, and the other is left in the 

 cyst. This cystenkern or feminonucleus is a useless residuum of 

 protoplasm in most forms, and occupies a more or less central 

 position with purely passive functions. It is certainly very inter- 

 esting in this connection to note Fleming's discovery, that sper- 

 matozoa and nuclei of ova consist of two substances, one readily 

 stainable, and one staining with difficulty chromatic and achro- 

 matic. He admits the existence of the spermonucleus and its mar- 

 riage with the feminonucleus in Echinoderms, describes the loss of 

 the tail which is composed of achromatic protoplasm, but consid- 

 ers that the feminonucleus of the ovum has a similar constitution 

 or is composed of stainable matter like the spermonucleus. 

 If this were unquestionable, the gonoblastic theory would be seri- 

 ously shaken. Fleming's figures, however, show decided morpho- 

 logical differences between the spermonucleus and feminonucleus 

 of the ova (Archiv. Micr. Anat. 1882), and this leads to doubts 

 as to the true import of his chromatic and achromatic sub- 

 stances, and whether they can be considered as tests of morph- 

 ological as well as physiological differences or similarities. 

 The researches of Frommann (Struk. Lebenser. und Reakt. thiers. 

 und pflanz. Zellen, Jena. Zeitschr. vol. xvn, n. f., Bd. x and 

 separate publication, Jena, 1884), have shown that the cell passes 

 through a series of metamorphoses, and has a life history durino- 

 which the nucleus arises by differentiation out of a primitive 

 mass or layer which is at first structureless and homogeneous 

 and is surrounded by granules and a layer of protoplasm which 

 he styles the hyaloplasma. Frommann's researches do not sus- 

 tain Fleming's discovery ; and Dr. Arnold Brass (Zool. Anzeio-. 

 Dec. 1883, p. 681) after studies made upon livino- cells in this 

 respect resembling those of Frommann, declares, that the chro- 

 matic substance is reserve food-material, which largely disap- 

 pears when cells are starved. This material is not, therefore 

 according to Brass, absolutely essential or even necessarily liv- 

 ing matter, whereas achromatic plasma is regarded as the essen- 

 tial living matter of the cell. 



Polaejeff (Sitz. d. Akad. Vienna, vol. lxxxvi, 1882), derives the 



