SUMMARY OF CURRENT RESEARCHES. 
35 
vertical partitions parallel to the first ; those of the lower half were 
uniformly vertical and parallel to the first cleavage plane. Those of the 
fourth order varied according to the direction of the third cleavages in 
the upper cells. Prof. Born discusses the problems which are raised by 
these observations on abnormal segmentation. 
Dr. W. Roux * * * § discusses Prof. 0. Hertwig’s recent investigations on 
the first cleavages of the frog ovum and their relations to organogenesis. 
He points out several sources of error in Hertwig’s work and dissents 
from his conclusions, holding firm to his own interpretation of the first 
cleavages as qualitative partitions of the material which serves for the 
direct development of the four quarters of the embryo. 
Ectodermic Origin of Skeletal Rudiments.! — Herr N. Goronowitsch 
complains that Miss Platt has not done justice to his prior research on 
the ectodermic origin of certain skeletal rudiments in the head of Verte- 
brates. Moreover, while Miss Platt states that ectodermic structures 
may be directly modified into cartilage, Goronowitsch maintains that the 
most one can say is that ectodermic proliferations give rise to skeletal 
rudiments of a connective tissue nature which become subsequently in 
part differentiated into cartilage. An ectodermic proliferation (behind 
the eye) which Miss Platt interpreted as indicative of a lost gill-cleft, 
and also connected with the basis in which the pterygo-palatine process 
developes, has nothing to do with either. It is “ Froriep’s rudiment ” in 
the region of the trigeminal. 
Human Embryo of Second Week.J — Prof. F. Mall describes a 
human embryo 10 mm. by 7 mm., apparently of the second week. He 
made sections and a reconstruction. The embryonic vesicle is attached 
to the chorion by a stem, and is composed of two layers between which, 
at a distance from the stem, there are indications of blood-vessels or a 
middle embryonic layer. Just beside the attachment of the vesicle to 
its stem there is a deep and short invagination of both layers. The 
author believes the specimen shows an inversion of the membranes, and 
that the invagination is the cavity of the amnion. 
Development of Hypophysis Cerebri in the Domestic Cat.§ — Mr. 
F. S. Aby, after a review of the very different senses in which the term 
pituitary body is used, comes to the conclusion that it is not synonymous 
with hypophysis cerebri, and should not be used for it ; nor should the 
term infundibulum be used for processus infundibuli. The sinus known 
as Seessel’s pocket has an epithelial lining which is only one cell veC 
thickness ; that lining the first signs of the hypophysis is several cells 
thick. The projection between the pocket and the hypophysis is formed 
by a proliferation of mesoblastic cells, and is not, necessarily, the remains 
of the oral invagination, although it indicates its position. The anterior 
end of the notochord is in close connection with this nest of cells, and 
does not approach the hypophysis cerebri. The epiblast which lines the 
encephalon and that which lines the stomodaeum lie in close contact in 
the region of the hypophysis. This last is developed from epithelium 
* Anat. Anzeig., viii. (1893) pp. 605-9. 
f Morphol. Jahrb., xx. (1893) pp. 425-8. 
% Anat. Anzeig., viii. (1893) pp. 630-3 (2 figs.). 
§ Bull. Laborat. Nat. Hist. Univ. Iowa, ii. (1893) pp. 295-310 (4 pis.). 
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