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SUMMARY OF CURRENT RESEARCHES RELATING TO 
Corpus Luteum of Mouse.* * * § — Dr. J. Sobotta finds that the corpus 
luteum of the mouse, the history of which he has traced, consists of 
enlarged epithelial cells within a connective-tissue framework. It is an 
organised structure, somewhat carcinoma-like, somewhat liver-like. It 
arises wholly from a hypertrophy of the epithelial cells of the Graafian 
follicle, without any process of proliferation. The only cells which 
multiply are the connective-tissue theca-cells, but neither they nor 
wandering cells have any direct share in forming the corpus luteum. 
Its development is very rapid ; in three days it is fully formed. 
Double Monsters. f — Professor 0. Schultze has been studying the 
effect of fastening tbe eggs of Bana fusca to glass slides, fertilising 
them, and then fixing them between slides so that they cannot revolve 
when turned upside down. It appears that a considerable number of the 
eggs exposed to the disturbing effects of gravitation develope into double 
monsters of various characters. Some develope two heads and two sets 
of gills on each. The formation of these double individuals is income 
way due to the rearrangement of the substance of the cell when in- 
verted and acted upon by gravity, so that the heavier part is drawn down 
and the lighter rises ; this results in a modification of the egg substance 
which acts like a partial division of the egg, and allows each of the two 
cells to develope somewhat as if isolated. As to the general question of 
the formation of double monsters in nature, the author thinks that the 
cause is to be found in some abnormal state of the ovarian egg. Double 
individuals may be regarded as coming from imperfectly divided ovarian 
cells ; a complete division of the germ material produces separate indi- 
viduals, a very slight division, double monsters ; between these extremes 
are identical twins. 
Development of Tarsus of Pelobates Discus.* — Herr M. Chomiakoff 
finds that the astragalus and the calcaneum have from the first their 
adult form and relative length. There is no trace of fusion out of 
several parts, nor of a distinct intermedium. The prehallux arises as a 
single rudiment, from which are differentiated first a basal and then a 
terminal segment. The basal segment is not a centrale (Howes and 
Ridewood), still less are the two parts cuneiforms (Duges). In the 
rudiment of the prehallux cartilage appears later than in the digits, 
and the structure must be regarded as secondary, and not as a sixth toe. 
As to the other parts of the tarsus, the earliest element is that which 
Gegenbaur and Hoffmann regard as the tarsal of the first digit. This is 
probably the centrale. The distal tarsals arise as a common rudiment, 
from which are differentiated first that (probably a fusion of two) which 
is opposite the second and third digit, and then that opposite the hallux. 
This last tarsal divides into two parts, so that there are four distal 
tarsals in the adult. 
Development of Amia, Lepidosteus, and Necturus.§ — Dr. F. 
Fiilleborn has a report on the results of his visit to North America to 
observe the development of these lower Yertebrates. He gives some 
* Anat. Anzeig., x. (1895) pp. 482-90 (7 figs.). 
t Arch. f. Entwicklungsmechanik, i. (1894). See Amer. Natural., xsix. (1895) 
pp. 287-8. X Bull. Soc. Imp. Moscou, 1894, pp. 351-6 (1 pi.). 
§ SB. Akad. Wiss. Berlin, 1894, pp. 1057-70. 
