ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
471 
Origin of Endocardial Epithelium in Salmon. * * * § — Dr. B. Noldeke 
has studied embryos of Salmo solar with reference to this question. He 
finds that the “ heart-cells ” of Ziegler are at least in part formed by the 
endoderm, but the absence of a distinct demarcation between mesoderm 
and endoderm in the region of origin makes it impossible to determine 
what part the two layers take in the process. He considers that the 
common statement that the endothelium of the heart arises wholly from 
mesoblast is entirely opposed to the conditions actually seen in the 
salmon. 
Sex of Hybrids. f — M. Henri Gadeau de Kerville calls attention to 
the fact that the results of successful hybridisation are much oftener 
males than females, and that male offspring are more numerous in pro- 
portion to the specific distance between the two parents. He regards 
this as supporting the position held in regard to the determination of 
sex by Messrs. Geddes and Thomson in their ‘ Evolution of Sex.’ 
b. Histolog-y. 
Practical Cytology. :j: — Dr. Y. Hmcker has produced a very useful 
introduction to cytology in the form of a series of practical lessons 
on the cell, the nucleus, karyokinesis, the ovum, the spermatozoon, 
maturation, fertilisation, and the like. His experience in conducting 
such a course for many years has made him aware of the material best 
suited for class purposes, and the results of this experience are now 
made available to other teachers. Each lesson gives an account of the 
• methods regarded as most effective, and a description of the selected 
objects ; the theoretical and historical aspects of the subject are also 
briefly alluded to. A carefully selected set of figures and references 
increases the value of the book, which impresses one as a very satisfactory 
piece of work. It will be of much service to teachers of histology and 
to private students. 
Experiments on the Regenerative Capacity of Striped Muscle. § — 
Prof. B. Morpurgo carefully removed a strip of muscle from the fore- 
limb of newly born white rats, and, by making an estimate ot the number 
of fibres : — (a)^in the excised bundle ; (6) in the muscle operated upon, 
after an interval of two months ; and (c) in a normal muscle ; reached 
the conclusion that the young muscle-tissue (whose i; elements were still 
multiplying by karyokinesis) has not the power of regenerating a lost 
strip. 
Longitudinal Growth of Striped Muscle.|| — Prof. B. Morpurgo 
finds that the distribution of the nuclei in the fibres of a muscle which 
has not attained its full length is exactly the same as that in the fibres 
of the full-grown muscle. The number of nuclei is strictly proportional 
to the growth in length. A new formation of muscle-nuclei continues 
in extra-uterine life long after the mitoses have ceased, so that the 
• mode of multiplication is doubtless amitotic. 
* Zeitschr. f. wiss. Zool., lxv. (1899) pp. 517-28 (1 ph). 
t Bull. Soc. Zool. France, xxiv. (1899) pp. 49-51. 
X ‘ Praxis und Theorie der Zellen- und Befruchtungs-lelire,’ Jena, 8vo, 1899, 
viii. and 260 pp. and 137 figs. 
§ Anat. Anzeig., xvi. (1899) pp. 152-6. || Tem. cit., pp. 88-91. 
