NOTES ON PLYMOUTH HYDROIDS. n 



furnish conclusive evidence in this matter. In living speci- 

 mens a division of sperm-cells with partially-developed flagella 

 was observed in the ectoderm. 



Asexual multiplication of P. pinnata. On April 23rd several 

 colonies of this species were brought in. which were peculiar 

 in having the ends of a number of hydrocladia greatly elon- 

 gated, destitute of hydrothecae and nematophores, and dis- 

 tinctly clavate at the tips. Such specimens were brought in 

 almost daily for some time, whenever the boat went out for 

 collecting. The first colonies found were isolated and kept 

 under observation. They rapidly increased in length, and 

 the terminal turgescence became more prominent. In three 

 or four days it was noticed that these enlarged ends were 

 forking and commencing to branch. 



In about a week after the first specimens were noticed, it 

 was found that the side of the jar in which the colonies were 

 confined was marked with closely adhering thread-like fila- 

 ments, which, on examination, proved to be the greatly pro- 

 duced hydrocladial extensions mentioned above, and they 

 were still connected with the colonies from which they sprung. 

 From these adherent extensions were crowing new colonies 

 of P. pinnata in various stages of development. 



After a time the connection between the parent colonies 

 and the young was severed bv atrophy of the connecting 

 hvdrocladial extension, rootlets were put forth from the 

 adherent portion or end of the original hydrocladia, and thus 

 young and perfectly independent colonies were produced 

 which grew rapidlv during the next few weeks. Another 

 group of colonies showing the hvdrocladial extensions was so 

 placed that the extensions could not touch the sides of the 

 bottle in which thev were kept. In this case the hydrocladia 

 grew and forked as before, and new colonies arose from the 

 forked ends of the hydrocladia. The parent stalks afterwards 

 died and fell to the bottom, giving the young colonies a chance 

 to attach themselves to the glass. 



This process reminds one so forcibly of the sending out of 

 stolons from which new shoots arise, as seen in many plants, 

 that I have proposed the name of stoloniferous reproduction 



