20 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
formed from the second and third clefts, and the details of the develop- 
ment show a condition similar to that in Ichthyopsida, hut also pointing 
forward to mammals. From the ventral thymus-mass of the third cleft 
the carotid gland is separated off, and seems to be homologous with the 
anterior epithelial corpuscle of amphibians. 
The anterior thymus of the lizard corresponds to the thymus of the 
second cleft in Ichthyopsida ; the posterior thymus of the lizard in its 
dorsal portion corresponds to the thymus of the third cleft in Ichthy- 
opsida ; but the ventral part is new. In mammals the thymus arises wholly 
from the third cleft, and is wholly ventral. From the fourth cleft in 
the lizard no dorsal thymus arises, but there is a transitory epithelial 
body. 
Early Development of Salamander.* — Herr Gronroos has convinced 
himself that in Salamandra maculosa the ectoderm cells of the lower 
half of the egg arise in loco from the coarsely granular yolk-laden cells, 
or in other words, are derivatives of the original macromeres. 
The Marsupial Larynx.f — Prof. Johnson Symington describes tho 
marsupial larynx, contrasting it with the larynx of higher mammals. 
In pouch specimens there is not only a well marked intra-narial glottis, 
but also a distinct arcus palato-pharyngeus , consisting mainly of a fold 
of mucous membrane, with only a thin sheet of muscular fibres between 
its two layers. These fibres do not form a distinct sphincter, but the 
naso-pharynx is closed during deglutition by mechanical means, the wall 
of the arcus being pressed by the food against the wall of the larynx. 
An obvious peculiarity of the marsupial larynx is the fusion anteriorly 
of the cricoid and thyroid cartilages, a union which the author regards 
as a secondary process. With regard to the true vocal cords, these are 
small and not readily distinguishable in many marsupials, but in pouch- 
specimens of Macropus bennetti they are well developed, and that of the 
adult Macropus must be regarded as degenerate. Prof. Symington points 
out the interest of this in connection with the voicelessness of marsu- 
pials, and suggests that they may be descended from a stock with a 
voice. 
Spermatogenesis of Dog-Fish.:}: — Herr B. Rawitz describes the 
division of testicular cells and the spermatogenesis in Scijllium canicula, 
with the particular end in view of discovering, by comparative studies, 
the general role of the attraction-sphere. He describes the processes of 
division concerned in the origin of the spermatocytes of the first and of 
the second order. Between the two there is a resting period, during 
which part of the chromatin-substance is reduced in amount, but there 
is no reduction-division in Selachians. After discussing the role of the 
attraction-sphere, and showing that it arises in the spermatids from the % 
central spindle of the preceding stage, he passes to the development of 
the spermatozoa, and shows that the middle portion arises from the 
attraction-sphere of the spermatid. 
Heteropagous Monstrosities.§ — Dr. L. Cerf describes the rare human 
monstrosity known as heteropagv, of which only four cases have previ- 
* Verh. Anat. Ges. xii. Vers., in Anat. Anzeig., xiv. (1898) Erg. -lift., pp. 261-4. 
t Journ. Anat. Physiol., xxxiii. (189S) pp. 31-49 (8 figs.). 
t Arch. Mikr. Anat., liii. (1898) pp. 19-62 (1 pi.). 
§ Journ. Anat. Physiol., xxxiv. (1898) pp. 706-19 (2 pis.). 
