38 EMBRYOLOGICAL MONOGRAPHS. 
PLATE XI. 
Development of ZoantHarta (AcTININE). Figures from Henri ve Lacaze-Durutiers, A. O. 
Kowatevsky, Ermenne Jourpax, Oscak Hertwic unp Ricuarp Hertwic, and ANGELO 
ANDRES. 
old. Blastoderm. om. Ovum. 
cil, Cilia. or. Mouth. 
ec. Ectoderm. pes. Foot. 
en. Entoderm. phe. Pharynx. 
g- Germ. phe. sac. Pharyngeal sae. 
g. vs.  Germinative vesicle. phe. sul. Pharyngeal groove. 
7g. mu. Longitudinal muscles. sg. cav. Segmentation cavity. 
mb. pa. Membrana propria. ta. Tentacle. 
mat. Mesenteries. te.cap. Testicular capsule. 
Arabie numerals are used to indicate the order of appearance of the mesenteries. 
The Greek letters show the order of the formation of mesenterial chambers and the order of the 
succession of the tentacles up to the stage with 12. 
1-25. Actinia mesembryanthemum. From Lacaze-Duthiers, Développement des Coralliaires. Premier mémoire, 
Actiniaires sans polypier. Arch. de Zool. exp. et gén., Tom. I. 1872. Plates XI.-XIII. 
1. A portion of an exclusively female mesenterial fold or septum, showing eggs with the germinative vesicle, 
and also dark, deeply colored germs no longer possessing a germinative vesicle. 
Nore.—In the original, more extensive, figure the eggs are shown to be often arranged in series. In 
the opinion of the author, this appears indicative of their common origin. 
2. A highly magnified spermatozoon. 
2a, Cells from the interior of a testicular capsule, in the condition in which they are found when they are 
mingled with mature spermatozoa. 
3. One of the reniform testicular capsules from a male mesenterial fold, rupturing and allowing the escape of a 
stream of spermatozoa. 4°. 
4. A germ at the time of its escape from the ovary. It appears bristling with prickles, which it afterwards 
loses. 
42, Portion of the external layer of the same, more highly magnified. £99. 
(At the bottom of the plate near the middie.) A germ in which there is a central deeply-stained mass 
(entoderm), and a peripheral layer (ectoderm) scarcely rose-colored. The depression which will be the 
mouth is indicated by or. The cilia are more strongly developed at the aboral pole. The striate appear- 
ance of the outer layer is caused by the presence of nematocysts which have begun to be developed in it, 
ao 
as well as by the cilia. About +44. 
6. An embryo seen in profile, and already presenting one partition (septum) indicated by a vertical line. 
The same as the last ; view of the oral pole. The mouth is elongated in the manner of a button-hole, the 
long diameter of which is perpendicular to the two septa, marked 1, which have divided the central mass 
of the embryo into unequal portions, a and a’. 
8. A slightly more advanced embryo seen from the side. The partitions, and especially the cesophageal pro- 
longation, cause the appearance at this point of the transversely oval cavity. 
9, A more advanced embryo, in which a second pair of partitions, 2, are visible. 
), Embryo showing plainly the division into four compartments. The chamber a! is already removed from the 
partition, 1, which gave origin to it; the chambers f, 8 form with a/a group of three lobes representing 
the greater of the two original chambers. 
1 
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