410 QUARTERLY CHRONICLE OF MICROSCOPICAL SCIENCE. 



the existence of such collar-bearing monads as these in parts 

 of the organism of some sponges, that Professor Clark objects 

 to the explanation by Haeckel of the structure of far more 

 complicated members of the class, by reference to the polyp- 

 type. He does not seem to see that whilst it is quite con- 

 ceivable that such forms of cells as ' collar-bearing monads' 

 should develop in parts of almost any organisms — ^just as 

 amoeboid cells, beaker-cells, flagellate cells, and a host of 

 other forms do — his insistance upon this point of structure 

 as conclusive of a relationship to flagellate infusoria leaves 

 the whole problem offered by the compound structure of the 

 calcareous and other sponges untouched. On the other 

 hand, this problem is dealt with, and the sponges are brought 

 into an intelligible position, by the mode of view advocated 

 by Haeckel, which view, by-the-bye, is that advanced, many 

 years since by Leuckart and by tVan Beneden, who said 

 " the sponge presents us with the prolyp-type reduced to its 

 simplest expression," 



Eimer (in ' Schultze's Archiv,' 2nd part, 1872) has figured 

 and described thread -cells from sponges of the genus 

 Reniera, and also well -developed, undoubted spermatozoa. 

 Huxley had seen spermatozoa in Tethya, Lieberklihn in 

 Spongilla, and Haeckel appears to have seen imperfectly 

 developed spermatozoa from various calcareous sponges, the 

 development of which, as modifications of the flagellate cells 

 of the entoderm, he describes in the ' Jenaische Zeitschrift,' 

 4th part, 1871. Haeckel, in this paper, whilst speaking of 

 the essential identity of the ciliary and amoeboid move- 

 ment of protoplasm, as proved by the conversion of amoe- 

 boid processes into waving cilia and vice versa, witnessed by 

 him in various cases (ova of Siphonophora, sponge-particles, 

 Magosphoera) and by the reporter in the development of the 

 zoosperms of the annelid Limnodrilus, places the movement of 

 zoosperms as a third kind of protoplasmic movement, which is 

 developed from ordinary ciliary movement just as that may 

 have been evolved from the amoiboid. The reporter would 

 venture to question very much the justice of this distinction. 

 The movement of the filaments of zoosperms is identical with 

 that of cilia in every way. No more striking proof of this 

 could be given than the movements of the aggregated zoo- 

 sperms in the spermatophors of oligochsetous Annelids, as 

 described in this Journal April, 1871. The mass of agglu- 

 tinated zoosperms exhibit a regular pulse-like or undulating 

 movement of their freely hanging filaments, in every respect 

 identical with that seen in the case of a ciliated epithelial surface. 

 Carter, in a recent number of the 'Annals and Mag. of 

 Nat. His/ (September), discusses Jaines Clark's suggestion 



