128 JULIAN S. HUXLEY. 



of collar-cell masses. In every case, they lived longer than the 

 collar-cell masses. 



The time that elapsed before all the collar-cell masses (whether 

 spheres or blown-out masses) in any one of these four cultures 

 had shown the first sign of impending death by contracting, was 

 from 6 to 12 days; the time before all the masses of a culture 

 were dead, from 8 to 15 days. The time which elapsed before 

 the normal regenerates in the same culture died, however, was 

 from 14 to 33 days ; in most cases, all normal regenerates lived 

 longer than any collar-cell mass in the same culture. Whether 

 this greater viability of the masses containing all kinds of cells in 

 approximately normal proportions was due to a protective func- 

 tion exerted by the dermal cells after their migration to the ex- 

 terior, or to the fact of some dermal or amoeboid cells serving as 

 food for the rest, or to other possible causes, remains to be seen. 

 In any case, the facts are interesting. 



A further observation may be referred to. It appears that the 

 spermatozoa of calcareous sponges have very rarely been ob- 

 served. Dr. Gatenby, of University College, London, who has 

 been working on the fertilization of sponges, was discussing the 

 subject with me, when I recalled that bodies resembling sper- 

 matozoa had been visible in some of my preparations of normal 

 regenerating masses from dissociations. 



Some of my slides I lent to Dr. Gatenby, who re-stained them, 

 and was thus able to discover certain interesting facts. The facts 

 are briefly as follows : Round the margin of all cell-masses from 

 some of my experiments are to be seen minute deeply-staining 

 bodies resembling spermatozoa with an ordinary elongated head ; 

 and groups of such bodies are usually to be seen in the interior 

 of the preparations. They are, however, totally absent from 

 other slides representing other experiments. There can be no 

 doubt that these are spermatozoa. The interesting point about 

 them is that they swarm round the masses of cells whether these 

 contain oocytes or not. I.e., such sponge spermatozoa are at- 

 tracted by somatic cells as well as by their proper partners. 



On re-staining, Dr. Gatenby found in the interior of many of 

 the somatic cells bodies which could be interpreted as heads of 

 spermatozoa which had been half converted into vesicular nuclei. 



