Mr. II. J. Carter on the Ultimate Structure of Spongilla. 21 



side, and thus to see down into the short wide oesophagus. 

 Such a view was obtained both by Mr. Busk and myself, and is 

 represented in fig. 9 6 of my memoir; but MM. Koren and 

 Danielssen seem only to have examined these parts from the 

 side. — I shall of course take the first opportunity of again 

 applying myself to the investigation; and if I find that I 

 have been in error, I shall lose no time in making public my 

 retractation. 



P.S. Since writing the above, I have been informed by 

 Dr. Dyster of Tenby, that he has repeatedly verified the most 

 important pai'ts of my observations ; viz. the development of 

 embryos, possessing a mouth and ciliated oesophagus, from 

 single ova, which are distinguished as such from the very com- 

 mencement, by the mode of segmentation and the presence of 

 the directive vesicles. 



IV. — On the Ultimate Structure of Spongilla, and Additional 

 Notes on Freshwater Infusoria. By H. J. Carter, Esq., 

 Assistant Surgeon H. C. S., Bombay. 



[With a Plate.] 



In the "Postscript" to my notes on the organization of Infu- 

 soria, dated 10th June last*, it is stated that apertures exist in 

 the investing membrane of Spongilla, and that the particles of 

 carmine taken in through them pass into the substance of the 

 sponge-cells. This was added chiefly to correct an assertion 

 made in the body of the pajier, that Spongilla lived by endos- 

 mosis. I also stated that I should recur to these facts more 

 particularly hereafter; but since then, up to within the last 

 month, I have not had an opportunity of again pursuing the 

 subject. I have, however, during this time, succeeded in ascer- 

 taining the ultimate structure of Spongilla, by following its de- 

 velopment from the seed-like body, and this I will now relate. 



Those who are acquainted with Spongilla are aware, that it is 

 charged towards the base with a number of seed-like bodies of 

 a globular shape, each of which consists of a coriaceous mem- 

 brane enclosing a number of delicate, transparent, spherical cells, 

 more or less filled with ovules and granular matter, while an 

 incrustation of gelatinous matter, charged with small spicules 

 peculiar to the species, surrounds the exterior of the coriaceous 

 membrane. It has also been shown that at an early period 



* Annals, vol. xviii. p. 242. 



