ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 149 
from one-half to two-tliirds of the whole egg ; the remainder is formed 
by a blastoderm with a blastoccel ; and the resemblance is heightened 
by the formation of a special layer of merocytes — a yolk-syncytium — 
beneath the blastoderm. Yet, if removed in due time from the abnormal 
influence, these eggs may give rise to segmented embryos with the 
normal complement of organs. Similar experiments were also made 
with the eggs of Bana fusca. The paper closes with a discussion of the 
conception of “ formative forces.” 
Post-Embryonic Development of Striped Muscle.* * * § — Prof. B. Mor- 
purgo has studied this in white rats. In the first period of extra-uterine 
life, the fibres of the skeletal muscles increase in number, and the pro- 
cess is introduced by a mitotic nuclear division in less differentiated 
elements. Thereafter no increase in the number of fibres occurs, but the 
nuclei multiply by amitosis as the muscles elongate. The subsequent 
thickening is solely due to increase of the contractile substance, — a 
process dependent on nutritive and functional conditions rather than 
on inheritance. 
Orthogene tic Variation in Chelonia.f — Dr. H. Gadow has investi- 
gated 20 newly-hatched specimens of the “ loggerhead ” turtle, Thalasso- 
chelys caretta , collected from one nest by Dr. Willey, supplementing 
this material by 21 newly-hatched and 15 other specimens of all sizes. 
The variations are very numerous and manifold. The number of 
median scutes varies between 8 and 6, and the lateral or costal scutes 
range between 7 and 5, and they are either symmetrical or uneven, 
there being perhaps 7 on the left and 6 on the right side, or vice versa. 
The normal shield possesses 6 median (including the so-called nuchal), 
and 5 pairs of costal scutes. Of the total of 56 specimens, not less 
than 43 are abnormal, = 76*6 per cent. ; of the 41 newly-hatched, not 
less than 38 are abnormal, = 92*7 per cent. The percentage of abnor- 
malities is four to five times as great in the newly-hatched as in 
the adult, and it decreases gradually from the smaller to the larger 
and very large specimens. The abnormalities are “ atavistic remini- 
scences,” from which most of the individuals rid themselves, and the 
reduction or squeezing-out of some of the soutes proceeds in a very 
regular way. “ Since the variations all lie in the direct line of descent 
(and the more serious the variation, the further back it points),” the 
author calls this kind of variation orthogenetic. 
Division-Processes in Primordial Ova of an Adult.J — Dr. W. 
Stoeckel describes a case in which a normal ovary in a woman showed in 
many of the primordial ova two nuclei, and in some cases three or even 
four. He maintains that this instance, which does not stand alone, makes 
it necessary to abandon the usual statement that there is no multipli- 
cation of ova or follicles alter uterine life. Abundant division seemed to 
be going on in this adult of 29 years of age. 
Nutritive Cells in Spermatogenesis.§ — Dr. K. Peter discusses the 
phenomena of spermatogenesis in representative types, and comes to the 
* Anat. Anzeig., xv. (1898) pp. 200-6. 
t Proc. Cambridge Phil. Soc., x. (1899) pp. 35-7. 
% Arch. Mikr. Anat., liii. (1898) pp. 357-84 (1 pi.). 
§ Tom. cit., pp. 180-211 (1 pi.). 
