ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 11 



vertebrates. Gotte has proved tliat a like origin obtains in the case 

 of Bombinator. The method of vertical sections used by these investi- 

 gators yields, in the present inquiry, views more trustworthy than 

 that of Fritsch. Also, it is plain that the distal extension of the 

 pineal gland, cursorily noted, may easily mislead as to its prosimal 

 origin. Besides indicating these sources of error, Dr. Eabl-Eiickhard, 

 by positive observations, confirms the results of Balfour, and leads us 

 to expect further original contributions to our knowledge of the 

 development of the cerebral centres among the other vertebrates. 



Tail in the Human Embryo.* — M. His in a paper on this question 

 disputes the assertion that has been made that at a certain stage in its 

 development the human embryo has a true tail, which is afterwards 

 absorbed. As to the definition of a tail, M. His considers that the 

 caudiform or tail-like prolongation is a true tail when, extending 

 beyond the cloaca, it contains a number, greater or less, of super- 

 numerary vertebra. Without this condition there is merely a caudi- 

 form appendage. The author knows of no well-authenticated case 

 of supernumerary vertebrae in the human embryo, and pathological 

 observation he believes to coincide with embryological knowledge in 

 justifying the assertion that in man the normal number of thirty-four 

 vertebrae is never exceeded. 



Structure and Life of Cells.f — Professor W. Flemming continues 

 his researches on cells and nuclei, this second Part comprising three 

 sections, with an introduction on terminology, and a short appendix 

 on technical methods. 



Almost the whole of the present part is devoted to the nucleus, 

 and especially to a critical study of its changes during division. In 

 its resting state, that stage which is most remote from division, the 

 nucleus consists of (1) an intertrabecular substance, traversed by the 

 (2) intranuclear plexus, with its (3) nodes, (4) nucleoli, and (5) 

 nuclear membrane. These parts bear the following synonyms : — 

 1, intermediate substance (Zwischensubstanz) ; 2, intranuclear struc- 

 ture (Flemming's own translation of Kerngeriist or Kernnetz) = 

 " framework " of Klein ; 3 (Netzhnoten) ; 4 (KernhorpercJien) ; 5 (Kern- 

 membran oder Wand). Flemming would no longer, as in Part I., 

 resolve the whole nucleus into Kernsubstanz and Kernsaft ; since 

 under the former we should then include the membrane and plexus, 

 together with the nucleoli. But these are of different nature. 

 Again, the Kernsaft, as Klein rightly urges, is not liquid. Kern- 

 substanz is better opposed in meaning to Zellsubstanz, that is, to the 

 extranuclear protoplasm. That chemical component of the nucleus 

 which is not affected by staining reagents, is now termed acliromatin, 

 in contrast to chromatin (by Flemming hitherto called " stainable 

 nuclear substance "), a word used without prejudice to future re- 

 searches touching the uniformity of the constituent thus designated 



* Arch. Sci. Phys. et Nat., iv. (1880) pp. 414-6. 



t Arch. Mikr. Anat., xviii. (1880) pp. 151-259 (3 pis. and 5 figs.). For a 

 notice of Part I. see this Journal, ii. (1879) p. 137. 



