and Physiology of the Spongioid. 25 



attempt to describe them all ; but when the observer knows 

 that they are the result of a polymorphic property, he will 

 not be surprised at seeing them differ entirely from the shape 

 which the spongozoon presents in the active living sponge in 

 situ or, at all events, immediately after it has been eliminated 

 for observation under the microscope by tearing a portion of 

 the Grantia compressor to pieces for this purpose. 



The spongozoon has its analogue, if not its identity, in the 

 solitary Infusoria, both marine and freshwater, first pointed out 

 and described by the late Professor James-Clark in America 

 (Mem. Bost. Soc. Nat. Hist. 1866, vol. i. pt. 3, pis. 9 & 10 ; 

 reprinted in the 'Annals,' 1868, vol. i. p. 133); in one speci- 

 men of which, viz. Codosiga pulcherrima (figs. 23 & 247/), the 

 " reproductive organ " is indicated — equal to our "nucleus." 



Development of the Ampullaceous Sac and Spongozoa. 



See 'Annals,' 1857, vol. xx. p. 26 &c, pi. i., and 1874, 

 vol. xiv. p. 400, pis. xx., xxi., & xxii. figs. 2, 23, for descrip- 

 tions and illustrations respectively. 



Ovum. 



For a description and development of the Ovum, see 'Annals,' 

 1874, vol. xiv. pp. 321-389, pis. xx., xxi., & xxii. 



Spermatozoa. 



See 'Annals,' 1874, vol. viv. p. 105, pi. x. 



Not being satisfied with my search after the spermatozoa of 

 sponges, I began earlier this year (1875) to examine Grantia 

 compressa, with the following results : — 



On the 29th of April, 1875. Gathered some branches of 

 Ptilota bearing Grantia compressa, placed them in sea-water 

 on the spot, brought them home, and in three hours after 

 gathering examined fragments of six, good, large living spe- 

 cimens successively, torn to pieces in sea-water, and placed 

 under £-ineh focus with high ocular. Ova generally about 

 3-6000ths of an inch in diameter (that is, a little less than 

 double the size of the spongozoon), actively polymorphic, and 

 all the parts visible and well-marked but the germinal vesicle. 

 No appearance of spermatozoa either in cells, free, or about 

 the ova. 



On the 5th of May, 1875. The same. Ova generally now 

 about 7-6000ths of an inch in diameter, and all parts, including 

 the germinal vesicle, well defined. No appearance of sperma- 

 tozoa. 



