PROJECTS FOli THE LMrROVE.MENT OF SPONGE-FISHERIES, 201 



APPENDIX. 



Eate of Growth in Sponges. — According to T. Lee (12), the fishermen 

 of Nassau say that the young sponge reaches marketable size three months 

 after its attachment. Lamiral (3), in his scheme for acclimatisation on the 

 French coast, stated that exhausted fisheries are regenerated in three years.* 

 0. Schmidt (6) "inclined to the opinion" that the growth of a self-sown 

 sponge was no faster than that of one of his cuttings, which were found 

 to take seven years to reach marketable size ; — it is noticeable that before 

 the experiment he had expected quicker growth (Lc. p. 776). The Florida 

 fishermen — v. Eathbun (11) — contend that "the Florida sponges grow much 

 more rapidly, and reach a fair size within a comparatively short period." The 

 Florida cuttings increased "to from four to six times their bulk" in six 

 months, but this growth was actually effected in two months, as " fully four 

 months elapsed before they recovered from the injury done them in the 

 cutting." 



If this last be accurate, then a cutting of 2| cubic inches, growing to five 

 times its bulk in two months, attained a volume equal to a hemisphere over 

 3 1 inches in diameter. Were it to proceed for the next two months at the 

 same rate, we should have a hemisphere over 6 inches in diameter, which is 

 more than marketable. Had the original 2^ cubic inches been produced at 

 the same geometric rate, then a hemisphere of 1^ inches in diameter would 

 have produced the six-inch sponge in six months. 



We have no right to assume this constant geometric ratio, nor to reason 

 elaborately from inexact statements about amputated fragments; but putting 

 these observations with the assertions of the Nassau and Florida fishermen, 

 there seems a balance of evidence against assuming in these localities a period 

 much greater than a year before the self-sown sponge becomes marketable. 

 The Levant variety, discussed by M. Lamiral, lives where the atlas shows a 

 mean annual temperature of about 7° F. below that of Florida, and the 

 Adriatic variety, investigated by Professor Schmidt, at a mean temperature 

 of about 7° F. lower still; we have no right to assume that the rates of 

 growth are identical. But since in the Adriatic the same grounds are said 

 (8) to be fished mercilessly, mature and immature, year after year,f there seems 

 to be great presumption against Schmidt's estimate ; and this estimate was 

 calculated from Buccich's cuttings, which I believe to have been unnecessarily 



* " On ignore quelle est au juste la duiee de la vie des Eponges et la vitesso de leur 

 accroissement ; cepundant, des la troisieme annce, on peut revenir pecher dans les lieux ou 

 elles avaient etc precederaent presque epuisees." — Lamiual, loc. cit. vol. viii. p. 329. 



t Probably based on Schmidt's own statement : " Man sucht in der schon beschriebenen 

 "Weise dieselben Standorto Jahr fiir Jahr ab. . . , niclit uur die ausgewachsenen, sondern 

 auch die kleineren Exemplare gcnommen werdcn." (Supplement der Spougion der Adria- 

 tischen Meeres, 1864, p. 25.) At tlie time of writing the text I could not refer to 

 Schmidt's original papers ; there is nothing to be added from them to the later account 

 of his experiments given by Marenzeller. 



r 2 



