322 DR. G. P. BIDDER : NOTES ON THE 



staining more darkly, in fig. 81). The indications seem to me that these 

 figures, Dandy's fig. 85, and many others in his very interesting plates — all 

 record stages in the war against Syncrypta, which appears to be carried on 

 successfully in Grantia either by the gonocytes themselves, or by other 

 amoebocytes which have this function *. 



Most interesting in this connection is Polejaeff's statement (1884, p. 72) as 

 to " spermospores " in Verongia : — ■" When ripe they recall so vividly the 

 corresponding formations in Sycon raphanus (with the sole distinction that 

 while in this latter instance the nucleus of the covering cell in quite ripe 

 spermospores is in most cases indistinct, in Verongia I find quite empty 

 capsules, nevertheless, provided with it)." 



All the " covering cells " represented in Verongia (pi. 10) contain only 

 masses of granules ; and similar masses are in Garteriospongia in an 

 endothelial chamber, as described by Schulze (and verified by Polejaeff) for 

 Oscarella, Aplysilla, etc. I suggest that the nucleus of the " covering cell " 

 is indistinct where the contained Syncrypta has killed the amoebocyte which 

 ingested it, and that those in Verongia are the nuclei of amoebocytes which 

 — as shown by their granular contents (as in my fig. 4) — have destroyed the 

 Syncrypta, themselves uninjured. An endothelial capsule occurs in Carterio- 

 spongia, instead of a covering cell as in Verongia, because the heap of 

 granules is 40 p. x 15 p instead of 9 p in diameter, showing that the 

 digested substance was too large for one phagocyte to contain. - Such 

 conclusions merely assume a process wholly comparable with the destruction 

 of Oscillatoria by the amoebocytes of Spongelia which is described by Cotte 

 (I. g. p. 455). 



As Vosmaer said (1887, p. 412): — 'The structures which many spong- 

 ologists have set forth more or less positively as spermatozoids may have 

 been so or may not; in many cases it remains doubtful.' 



Note E. — Origin of Sponges. 



If the hypothesis be adopted that the granules of porooytes attract 

 spermatozoa, a possible history of the origin of sponges is suggested. 



If we construct our imaginary ancestral sponge on the lines of the Sycon 

 amphiblastula, illumined by Protospongia, we find a colony of flagellate 

 collared cells whose function is to obtain nourishment, surrounded by their 

 associate archaBocytes, which receive the digested nourishment and alike 



* I am unaware how far, by those who have worked at these problems, phagocytosis and 

 conjugation are considered cognate or opposite. My friend Miss E. R. Saunders tells me 

 that in the revival of a plasmodium of Myxomycetes from the sclerotial condition, as each 

 sclerotial cyst is enveloped by the advancing plasmodium, it is uncertain for a moment 

 whether a vacuole will be formed round its protoplasm and this be digested, or whether it 

 will revive rapidly enough to burst to the moisture, and unite alive with the syncytium. 

 This alternative absorption as food, or as a living partner, suggests that conjugation may arise 

 from attempted phagocytosis. 



