Presence of Spermatozoa in the Spongida. 105 



we must also conclude that the whole bunch is produced in 

 one cell ; but I have not yet seen an instance of it. If de- 

 veloped from the granules of the nucleus, the whole of this 

 body of the latter might thus pass into one of these "rosettes." 

 In one cell I observed two twe^Manchorates together end to 

 end, or slightly overlapping each other ; but this was in the 

 e^wianchorate stage — that is, when neither of these embryo 

 spicules exceeded 2-6000ths of an inch in length (fig. 14). 



In order that the full size of the flesh-spicules of Esperia 

 wgagropila,Qi. (Ilalichondria wgagropila, Johnston), might be 

 compared with the embryonic ones in their mother cells 

 respectively, figures of the inequianchorate (fig. 12, a, b), 

 bihamate (fig. 10), and tricurvate (fig. 3) of Bowerbank 

 {Haken, Spangen, and Bogen of Schmidt) have been repre- 

 sented on the same scale among the illustrations. 



On the Presence of Spermatozoa in the Spongida. 



In January 1856, Lieberkiihn observed, with reference to 

 my figures conjecturally termed " zoosperms in Spongilla " 

 ('Annals,' Nov. 1854, vol. xiv. pi. xi.), that they were not so, 

 but those of " Trachelitis trichophorus " (Miiller's Archiv f. 

 Anat., Phys. &c. p. 18) ; and, so far as the negative goes, I 

 believe he was right. 



But in August 1856, two years after the " zoosperms in 

 Spongilla " appeared, I also published a figure of a minute 

 monociliated sponge-cell attached to a much larger unciliated 

 one, with the following explanation in the index to the plates, 

 viz. " Fig. 43. Small sponge-cell with so-called ' zoosperm ' 

 attached, &c. " (Annals, vol. xviii. p. 245, pi. vi.), and in the 

 figures close to it, viz. 45 to 48, four representations of Astasia 

 limpida = Trachelitis trichophorus, Ehr.,with anatomical detail. 



Now, without reference to the identity here of the smaller 

 monociliated sponge-cell with a spermatozoon of Spongilla, I 

 would submit to the reader whether (on comparing all these 

 figures, which are within an inch of each other in the same 

 plate) it is likely, as implied by Lieberkiihn (I. c), that I could 

 have mistaken a sponge-cell for a Trachelitis trichophorus, 

 especially as I allude, in the text of my paper on the supposed 

 " zoosperms in Spongilla" to the cilium as the " tail " — seeing 

 that the sponge-cell is propelled by the cilium from behind, 

 and Trachelitis trichophorus drawn on by the cilium in front, 

 as shown respectively in the figures to which I have just 

 alluded. 



With the explanation of this little difference, which may 

 also tend to show the distinction between a monociliated 



