586 REPORT— 1898. 



served, some on January 5, at 10.30 a.m., in Hermann, others on January 

 5, at 8.10 P.M., in No. 3 mixture. The use of this method was not, on 

 the whole, satisfactory, as many of the embryos obtained in the last series 

 were clearly moribund ; but as some of the oldest embryos of the series 

 were perfectly healthy, and show beautiful karyokinetic figures in the 

 sections, it is probable that renewed experiments with it would be 

 successful. 



Another female colony, together with a male colony, wei-e isolated in 

 a bell jar which was allowed to float in one of the tanks. The embryos 

 collected from this were at first healthy, but after twenty hours the water 

 became foul and the embryos died. 



These two experiments, to isolate individuals and to endeavour to 

 obtain the exact ages of the embryos and others that were tried, have 

 given me some data, but cannot be said to have been thoroughly satis- 

 factory. Mr. Wadsworth's time during his stay at the laboratory was 

 very largely occupied in collecting and preserving the embryos that were 

 found free in the large tanks, and these have yielded some very fine series, 

 the most successful of which are those preserved in Rabl's fluid and in 

 the No. 3 mixture. Before leaving the laboratory Mr. Wadsworth cut 

 open a number of female colonies and preserved the eggs from the 

 coelentera. 



Since Mr. Wadsworth's return a very large number of complete series 

 of sections through the embryos have been cut, stained, and mounted, and 

 I have carefully examined them, making notes and drawings of interesting 

 points. As the work is not yet finished, and there are still many speci- 

 mens to examine, it would be premature to do more than to point out 

 some of the results of the investigation. These results are given' only 

 provisionally, and will be subjected to confirmation .or the reverse before 

 being finally published with the illustrations. 1. The ovum of Alcyonium 

 is never fertilised before it leaves the body of tlie parent. 2. Soon after 

 leaving the polyp the ovum enlarges, probably by the absorption of water, 

 and the membranes covering it are broken and lost. 3. The nucleus 

 which is at the edge of the ovum diminishes in bulk, and is then dissi- 

 pated and lost to view. No karyokinetic figures accompany the.se changes 

 in the nucleus. I may add here that these observations confirm the 

 results I have obtained from material collected in the winters 1893-4, 

 1895-6, 1896-7. 



4. Another nucleus, much smaller than the germinal vesicle, may be 

 found in the ovum in what appear to be later stages. This is accom- 

 panied by archoplasm (?), and travels towards the centre of the ovum and 

 then fragments. 



5. Segmentation is very irregular in Alcyonium, as it is in Renilla, 

 according to Wilson. Sometimes embryos with four, eight, or an irregular 

 small number of well-defined blastomeres are to be found, but more fre- 

 quently — perhaps normally — no segmentation occurs for some time, and 

 then the embryo segments into twenty or more tightly-packed blastomeres, 

 the outlines of which cannot be seen from the outside at all. 



6. In all the well-preserved embryos which are segmented the nuclear 

 structure is clear and definite, and in most of my series beautiful karyo- 

 kinetic figures may be seen in one or more of the segments. 



7. A complete series of the later stages of development up to the time 

 of the formation of the mouth has been obtained. This series will be 

 studied when the earlier stages have been more satisfactorily worked out. 



