SCIENCE- GOSSIP. 



3*5 



reproductive organs are beautiful, the tetraspores, 

 like the preceding species, bearing a hand-like 

 resemblance. They are found thus only in winter. 

 Harvcyilla mirabilis (fig. 3) : this tiny plant grows 

 on the previous species in the form of a very 

 minute globose body, looking to the naked eye 





Fig. 3. Harveyilla mirabilis. 



like a fruit of its host. I have observed it in 

 various stages of growth, and have found all three 

 reproductive organs. The larger plants prove only 

 to be vegetative after having fulfilled their pro- 

 pagation. Certain sections in the slide show tetra- 

 spores. The larger cells are part of the filament 

 of the host. Bryopsis plumosa belongs to the 



m i 



Fin. 4. Polysiphonia nigrescens. 



Chlorosperms, or green sea-weeds, and is an object 

 of great beauty when seen in the tide pools, looking 

 like minute green feathers. Reproduction is by 

 the direct change of the endochrome into zoospores. 

 PolysipJionia nigrescens (fig. 4), P. atro-rubescens 

 (fig. 5), and P. brodiaci (fig. (j), are three species 



of a very interesting order of sea-weeds, which 1 

 have put in to show the structure of the so-called 

 siphons. [These would be only shown in a cross- 

 section of stem; see Mrs. Major's note. — Ed. Micro- 

 scopy, S.-G.] In P. nigrescens and P. atro-rubescens 

 tetraspores are seen, whilst P. brodiaci has beautiful 

 urn-shaped cystocarps. Callith amnion corymbosum 

 does not occur on our coast at Deal, but is found 



Fig. 5. P. atro-ruhescens. 



on the Devon and Cornish coasts, and is a most 

 beautiful microscopic object. Delesseriasanguinea 

 (fig. 7) : having found the reproductive organs 

 this winter, I am sending them in as fresh a state as 

 possible. I am of opinion that another mode of 

 reproduction exists, as I have found old plants with 

 young fronds as perfect as their parent fronds 

 were when in their summer beauty. 



Eemarks. — I must apologise for having kept the 

 box past the allotted time ; but these special series 

 are of exceptional interest to me, and the system is 

 well worthy of imitation. In the specimens re- 

 ferred to, will be remarked the special inclination 

 of the marine algae for the tetraspore or vegeta- 

 tive form of reproduction. When one considers 

 the vast volume of the surrounding water one 

 cannot help marvelling at the immense numbers of 



If 



Mi 



Fig. 6. P. brodiaei. 



antherozoids, or better pollinoids, which must be 

 produced in order to- keep up the intermittent 

 sexual generation. Probably many millions of 

 pollinoids are wasted for every one that fulfils its 

 life's object, whilst every tetraspore that is de- 

 tached has a igood chance, of becoming a perfect 



