100 Mr. H. J. Carter on the Origin 



long dryness, from the subsidence of the water in which they 

 dwell ; while the marine sponges, in which the absence of a 

 seed-like body is as constant as its presence in the freshwater 

 sponges, not only in many instances are never uncovered, 

 but under no circumstances can be long so, by the sea. 



In Bombay most of the freshwater sponges grow many feet 

 above the bottom of the tanks, probably for the sake of purity ; 

 so that as the water is withdrawn for domestic purposes, they 

 are soon left dry, in horizontal lines which they occupy along 

 the sides. Under these circumstances, most of them are 

 uncovered by water for six months at least during the year ; 

 while their increase is so rapid that herbaceous plants which 

 spring up just below the water's edge in the month of 

 July, may have pieces of Spongilla Carteri about them, two 

 or three inches in diameter, by the time the water again begins 

 to recede from these plants in the following October and 

 November. 



At last, then, the true nature of the seed-like body of the 

 freshwater sponges appears to be thus revealed. It is an 

 assemblage of ova, which are at once developed together into 

 a young Spongilla ; and hence my statement in the last 

 volume of the ' Annals ' (p. 436), that the ampullaceous sac is 

 Hackel's Gastrula developed in situ. 



On the Origin or Mother Cell of the Spicule in the Spongida. 



In August 1856, Liebei'kiihn published, as one of the results 

 of his study of Spongilla, that the spicule originates in the 

 interior of a cell, " die Kieselnadeln entstehen innerhalb der 

 Zellen," which had been illustrated in the preceding " Heft " 

 (Muiler's Archiv f. Anat. Phys. &c. Hefts iv. & v. p. 513, 

 and Tab. xv. fig. 22, respectively). In this figure the spicule 

 may be observed to be enclosed by a cell bearing a distinct 

 nucleus and granules. 



In the following April (1857), my paper on the "Ultimate 

 Structure of Spongilla " was presented to the Bombay branch 

 of the Royal Asiatic Society (B. B. A S. Journ. vol. v. p. 574) , 

 and reprinted with illustrations in England ( l Annals,' July 

 1857, ser. 2. vol. xx. p. 21, pi. 1), where in fig. 8 will be found 

 an almost fac-simile of Lieberkuhn's representation, with the 

 exception that in the former the spicule appears to have been 

 smaller. That there should be such a close resemblance 

 between our figures is not extraordinary, because we were 

 studying the same organism with a similar purpose, about the 

 same time, although one of us was at Berlin and the other at 

 Bombay, thus working independently of each other. 



