Mr. H. J. Carter on the Reproduction of Sponges. 423 



which presented bodies in its interior similar to a brood of 

 cells, which, on other occasions and nnder similar appearances, 

 I have found to issue in the form of ciliated, monadic, poly- 

 morphic Rhizopods. With these also were present a number 

 of much larger round and subround refractive cells, in which 

 a nucleus was present, but very difficult to be seen, owing to 

 the extreme fineness and apparent homogeneity of the mate- 

 rial they contained. There were also several starch-grains 

 present ; and on many occasions, but on one in particular, a 

 pair of these Diffiugice in zygosis, when crushed in water 

 under the cover of the slide, presented in their interior, besides 

 a great number of the three kinds of cells mentioned, a still 

 greater number of ciliated, monadic Rhizopods, of the sizes 

 of the bodies in the nuclear cells, and a number of small 

 unciliated Amosbce, about the size of the ' refractive cells.' 

 So far, then, only, do I feel justified in stating that this ap- 

 pears to me to be the mode in which the impregnated genera- 

 tion of Diffiugia is produced ; and if it be so, then all that 

 remains to prove it is the evidence afforded by witnessing the 

 actual union of the ^ ciliated monadic Rhizopods ' with the 

 ' unciliated refractive cells ' — an act which, probably taking 

 place within the body of D. urceolata in an undisturbed con- 

 dition, is not likely to be soon seen among its contents when 

 forced out of the test into water by crushing and the pressure 

 of a glass cover " (Annals, 1865, vol. xv. p. 171 et seq.). 



I have quoted this paragraph at length, not only to 

 show the results of my last observations on zygosis, but to 

 point out what may take place in the sponge-animalcules 

 under similar circumstances, if we can satisfy ourselves that 

 they also enter into this kind of union. But before com- 

 mencing this part of our subject, it is also desirable to add 

 briefly what I have observed in the oviform bodies of the Dif- 

 JlugicBj which we may assume to be the result of their zygosis. 



One thing is always obvious, viz. that the nucleus disap- 

 pears, leaving the nuclear utricle empty ; and the changes 

 which take place in the oviform bodies in EugJgpha are recorded 

 in the following extract, viz. : — " I have seen the ovule of 

 Euglypha in every stage, from its first appearance in the test 

 to the time when it has acquired the power of putting forth 

 rhizopodous prolongations (fig. 31), after which the tests of 

 very small Euglyphm presented themselves in the same basin, 

 which did not appear before the parents had died off and left 

 their ovules to shift for themselves " (Annals, 1856, vol. xviii. 

 p. 230, pi. 5). All this was described and figured in the place 

 just mentioned, more than fifteen years ago. 



We are now in possession of the form of the sponge-ani- 



