Ou the Structure and Development of Argiope. 509 



fimctiou of discliarging the eggs. The liuing layer of cells is ciliated. 

 The cilia of the fimnel take up the eggs whieh also pass aloug the ovi- 

 ducts by the action of cilia and then enter the brood pouch where the 

 early stages of their development up to the formation of the free swim- 

 ming larva take place. 



The brood pouches (figs. 2, 7, and 8, hd. jr, are invaginations of the 

 lateral body wall; they lie behiud the posterior border of the lopho- 

 phore. A similar pouch , in which the eggs undergo their early devel- 

 opment , is described by Lacaze-Düthiers in Thecidium , but here it 

 is median and unpaired. 



Morse ^ has described in Terebratulina the escape of the egg from 

 the mother, but he is not certain whether fertilization takes place before 

 or after this occurrence. In Argiope it must of course take place while 

 the egg is still connected w^ith the mother, but it is doubtful whether in 

 the brood pouch or in the body cavity, but the facts that the outer open- 

 ing of the oviduct is very small and that the cilia work outvvards, point 

 to the former place. Brachiopods generally live together in colonies and 

 the spermatozoa are probably discharged by the male into the water, 

 and some of them reach the female in the streams of water set up by 

 the ciliated tentacles. 



When taken out of the brood pouch the eggs and young embryoes 

 only live a few hours, so that one's observations were necessarilj^ con- 

 fined to these stages which were existing in the Argiope at the time 

 the Shell was opened. To render these observations complete required 

 a greater quantity of material than was at my disposai. 



Like KovvALEVSKY 2 ^ I have unfortunately not succeeded in seeing 

 the segmentation of the egg, however once I found two ova which had 

 divided into two Segments , and one of the cells of one of them showed 

 traces of a secondary division (figs, 21 and 22). The next stage con- 

 sisted of a blastosphere 5 the cells here like those of the egg and of the 

 embryoes are crowded with granules , of a deep brick red color and 

 very small. These characters render it very difficult to observe the 

 outlines of the cells or their nuclei. 



The cells at first are very cylindrical and the segmentation cavity 

 consequently small, but when the blastosphere is mounted in glycerine, 



1 Embryology of Terebratulina. Memoirs of the Boston Society of Natural 

 History. Vol. II. 



- Observations on the Development of Brachiopoda. Moscow 1874. —Also: 

 Observations sur le Développement des Brachiopodes. Analyse par U. M. Oehlert 

 et Deniker. Archives de Zoologie Experimentale et Generale. 2me gér. Tome I. 



