MEDUSA. OF MICRO HYDRA RYDERI. 643 



with a pipe (the hot-water pipe in the Victoria Regia taiih). 

 This fact leads me to the inference that the polyps were 

 developed from germs contained in the water which I brought 

 away Avith me, for I do not see how they could have got there 

 while the sponge was alive ; moreover, they were in diiferent 

 stages of development, the earliest stage seen by me being 

 a little mound of fuscous coloured sarcode.'' Fowler has 

 figured a section of a bud, which " may either remain attached 

 to the parent, or may be nipped oif and settle close by, its 

 tissues in either case gradually undergoing the differentiations 

 which characterise the adult." 



The sexual method of reproduction of Microhydra is no 

 doubt by means of Medusae. Up to the present time only the 

 earliest stage of the Medusa is knowu. The young Medusa 

 has the appearance of an Anthomedusa, but it is impossible 

 to assign it to a definite family until the later stages have 

 been seen. It would be most interesting to know Avhat 

 became of the Medusa after leaving the Hydroid. The Medusa 

 is set free in a stream or river, so that it must be carried aloug 

 with the current in the direction of the sea. 



The exact method of the sexual reproduction of Limno- 

 codium still remains a mystery. During the period it lived 

 in England only the male Medusa was found, and not the 

 slightest evidence on the presence of the female sex was 

 obtainable. The Medusa has not been seen in England since 

 1893, so it is evident that our stock has completely died out. 



In 1901 Limnocodium suddenly appeared in the Victoria 

 Regia tank at Lyons, and an account of it is given by Vaney 

 and Conte. The Hydroid phase was searched for, but was not 

 found, and the Medusas were all males. 



In 1905 Boecker recorded the appearance of Limno- 

 codium in the Victoria Regia tank at Munich, and again 

 only males were seen. The author does not mention the 

 occurrence of the Hydroid phase. 



