The Microscope. 171 



and especially of the solubility of nuclein in dilute alkalies and 

 concentrated acids ; and in 1879 even before Flemming had used 

 the term chromatin he had already expressed his opinion which 

 considers the coloring substance in the nucleus as none other 

 than the nuclein of Miesher, and he has, since 1879, employed 

 this term in his laboratory at Louvain. In 1881-82, Zacharias 

 arrived at the same conclusion and by the same means. Most 

 authors who follow Flemming regard the reticulum or chromatin 

 as fibrous, and as a typical structure of the nucleus, but Balbiani 

 in 1886 remarked in the larvse of Chironamus, that the coloring 

 part of the nucleus is a continuous tubule, and quite naturally 

 suspected this to be the case in all nuclei, and this Strasburger 

 in 1882 affirmed, although his observations were limited to a 

 few nuclei of vegetable cells. 



Rauber in 1882 states that the chromophilous part of the nu- 

 cleus may present a reticulate, a filamentous or a globoid form. 

 Outside of this reticulum or, more correctly, nuclein tubule, ac- 

 cording to all modern authors, if we except Zacharias, there exists 

 also a sap, or homogeneous fluid, which is very aqueous, without 

 granules, or any other bodies of a particular shape (this is the 

 achromatin of Flemming, the " Kernsaft " of others), and often 

 there are to be seen in this fluid one or more nucleoli, the nature 

 of which as yet remains to be determined. 



With regard to the membrane of the nucleus there are many 

 contradictory opinions ; Peitze'r, Retzius and Brass deny its ex- 

 istence, others who admit it consider it with Flemming as belong- 

 ing to the nucleus proper, either as depending on the chromatin 

 or not, and others with Strasburger regard it merely as a con- 

 densed layer of the surrounding protoplasm. In 1883, Prof 

 Carnoy in the Prospectus of his treatise on Cellular Biology 

 calls attention to another element existing in the nucleus ; besides 

 the nuclein he affirms there is also a true protoplasmic portion, 

 consisting of a real reticulum and enchylema similar to those of 

 the protoplasm outside of the nucleus. The structure of the 

 nucleus, however, remains still buried in darkness, and in 1883 

 Rauber declares it to be still a scientific puzzle. 



In 1884 appeared the first text-book of Cellular Biology, by 

 Canon J. B. Carnoy, Professor of Cytology at the University of 

 Louvain. I learn from the author that the first edition is already 

 out of print, and the work is not yet completed. C. S. Minot,. 



