202 I'UOJECTS FOR THE IMPROVEMENT OF SPONGE-FISHERIES. 



injured by exposure to air, by the trepanned perforation, and by too close 

 planting so as to choke each other. 



The much-needed observations on the natural growth of commercial sponges 

 could probably be best made by observing the seedlings on a small marked 

 area, artificially cleared. Single sponges fixed on stones could also have labels 

 attached with silver wire, and be examined periodically. 



That the rapid period of growth suggested by the fishermen is not impos- 

 sible, is shown by a few observations which have been made on calcareous and 

 siliceous sponges. Vosmaer (9) calculated the giant Sycon on the oyster- 

 frames to grow 1 to 2^ inches in length in a fortnight, and (10) found the 

 bud of a Tethya in a month as large as its mother, ^ inch in diameter. 

 Bowerbank (4) quotes H. Lee, that in the Brighton Aquarium Hymeniacidon 

 formed in five months a crust 1 foot in diameter. Of this sponge and of 

 Halichondria numerous large crusts may be observed in sjmng on the rocks 

 near Plymouth Laboratory; they appear rarely to survive the summer, and 

 Johnston (1) states that many allied species are annual. Carter (2) found 

 Spongilla, at Bombay, grow over a surface two or three feet in circumference in 

 nine months ; and states that specimens growing on straw in the water reached 

 a thickness of half-an-inch in a few days, before the straw in the water had 

 changed colour. 



The growth of horny sponges may easily be much slower than in these 

 instances, but as yet I know of no reason to assume so. 



REFERENCES TO QUOTATIONS. 



1. Johnston, G. (1842). — "History of British Sponges and Lithophytes," p. 92 and 



p. 124. 



2. Carter, H. J. (1649).— Annals and Mag. Nat. Hist. pp. 95 and 96. 



3. Laniiral, E. (1861-1863).— ^u/i. Soc. d'Acclim. Paris, vol. viii. p. 327 ; vol. ix. 



p. 641 ; vol. X. p. 8. 



4. Bowerbank, J. S. (1874). — " Monograph of British Spongiadse," vol. iii. p. 339. 



5. Hyatt, A. (1875 and 1877). — Mem. Boston Soc. Nat. Hist. vol. ii. quoted here 



from "U.S. Fish. Comm.," "Fishery Industries" (4to.), Sect. i. pp. 845, 846. 

 6 Marenzeller, E. von (1878). — Verhandlung der K. K. Zool. Bat. Gesellschaft in 

 Wien, quoted here from translation in " U.S. Fish. Comm. Report " (Svo.), 

 1879, p. 771, et seqq. 



7. Schulze, F. E. {1819).— Zeitschr. wiss Zool. vol. xxxii. p. 617 and p. 642. 



8. Faber, G. L. (1883).— "Fisheries of the Adriatic," p. 96. 



9. Vosmaer, G. C. J. (I88i).—Mitth. Zool. Stat. Neapel, vol. v. pp. 486 and 487. 



10. Vosmaer, G. C. J. (1887).— "Bronn's Klass. u. Ord. d. Spongien," p. 440. 



11. Rathbun, R. (1887).— " U.S. Fish. Comm., Fishery Industries" (4to.), sect. v. 



vol. ii. p. 832. 



12. Lee, T. (1889).— "U.S. Fish. Comm., Report of Comm. for 1886," p. 664. 



13. Browne, E. T. (1894).— Trans. Liverpool Biol. Soc. vol. viii. p. 45. 



It will be seen from this list how greatly I have been aided in com- 

 piling these notes by the most valuable publications of the United 

 States Commission of Fish and Fisheries. 



