418 Mil. F. E. EEDDARD ON 



fairly confident that the phagocyte theory is the correct one to 

 explain the anomalous appearances seen in the case of the sperma- 

 tophores of this Fheretima. As to the origin of the phagocytes, 

 I have no facts to offer. This is, however, not a weak point in 

 the ai'gument that the}'' are phagocytes. The cells are as cells 

 small; the nucleus is very large compared with its surrounding 

 protoplasm. But the immense numbers of the cells makes up 

 for the lack of non-nuclear protoplasm, and the large nuclei are 

 an indication of their activity. The presence of these cells leads 

 to the rapid and dark staining of the spermatophores, which is 

 very noticeable, and not what would be expected in such a 

 structure, on the view that its walls were entirely chitinous. I 

 obtained the clue to the nature of the processes going on in the 

 spermatophores of this 01igocha,'te when within the spermatheca 

 by a consideration of an important recently published paper by 

 Di'. Cognetti de Martiis. The author promises a further contri- 

 bution on the role played by phagocytes in the destruction of 

 superfluous spermatozoa ; but this memoir I have not yet seen. 

 In the memoir which I have read and the title of which is quoted 

 below *, Dr. de Martiis observed that the spermatozoa leave the 

 large spermatophore, and suggests that the fibrils of the wall of 

 the latter are caused to diverge, and thvis leave room for the exit 

 of the spermatozoa, b}'' the action of certain cells against which 

 the end of the spermatophore is pressed, and which form part 

 of the lining epithelium of the spermathecal sac, A chemotactic 

 influence leads on the spermatozoa from cell to cell until they 

 reach the egg-sacs. He thinks that the weak and dying sperma- 

 tozoa are devoured by phagocytes, and has figured spermatozoa 

 in the interior of phagocytes. This, however, is a quite difierent 

 series of events from what takes place, as I believe, in Pherethna. 

 Here, I repeat, there is some evidence for regarding the phago- 

 cytosis of the walls of the spei-matophore as a means of libei-ating 

 the enclosed sperm. 



The contents of the spermatophore now demand attention. 

 The cavity of the spermatophore is not entirely filled with 

 spermatozoa. As will be seen in text-fig. 135, the mass of sperma- 

 tozoa is limited to the lower half of the spermatophore. It 

 occupies hardly half of the whole space available. The mass 

 of spermatozoa is strictly delimited above, and the line of demar- 

 cation is a regularly curved line. I think it possible to detect a 

 delicate membrane surrounding the mass of spermatozoa and to 

 be distinguished from the substance to be shortly described which 

 fills up the rest of the cavity of the spermatophore. The inclusion 

 of the spermatozoa in a case independent of the case of the 

 spermatophore itself, and lying within it, is a fact of likeness 

 to the spermatophores of Benhamia T, where something of the 

 same kind occurs. It is possible also that the delicate case of 

 the spermatozoa is fabricated in the appendix of the spermatheca, 



* "Contributo alia Conoscenza della fecoiidazione negli Oligoclicti," Atti Ace. 

 Sci. Torino, xlv. 1910. 

 t P. Z. S. 1901. 



